Hi,my problem is when I choose yes to go for customer number 2 and when I simply choose either a combo(even thought A,B,C or D) it will straight end the whole program and show press any key to continue instead of continue the looping for return the selection(case A,B,C,D or Q).

#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>
#pragma warning ( disable : 4996 )
#define COMBO_A 10.00
#define COMBO_B 15.00
#define COMBO_C 18.00
#define COMBO_D 24.00
#define SST_RATE 10.00

//Function Declaration
void logo(void);
void menu(void);
int order(void);
int dailysalesreport(void);

//Global Variable
int customer, totalCust, quanA, quanB, quanC, quanD, salesAmount;
double SoldA, SoldB, SoldC, SoldD, totalTax, totalRM;

int main()
{
    //Local Variable
    char selection, again;
    int  numComA, numComB, numComC, numComD;
    double comboCharge, totalToPay, changeDue, amountPaid, totalComA, totalComB, totalComC, totalComD, tax, subTotal;

    //Display
    logo();
    menu();
    customer = 1; //To Display Customer Number
    printf("  Customer No : %d\n", customer);

    //Starting value
    comboCharge = 0;
    subTotal = 0;
    SoldA = 0;
    SoldB = 0;
    SoldC = 0;
    SoldD = 0;
    totalTax = 0;

    //Looping
    do
    {
        selection = order();//call function

        switch (toupper(selection))
        {
        case'A':
            printf("  Enter Quantity > ");
            scanf("%d", &numComA);
            totalComA = numComA * COMBO_A;
            printf("  Combo A : %d @ RM10 = RM%.2f\n\n", numComA, totalComA);
            subTotal += totalComA;
            quanA += numComA; //for dailysalesreport
            SoldA = quanA * COMBO_A;  //for dailysalesreport
            break;

        case'B':
            printf("  Enter Quantity > ");
            scanf("%d", &numComB);
            totalComB = numComB * COMBO_B;
            printf("  Combo B : %d @ RM15 = RM%.2f\n\n", numComB, totalComB);
            subTotal += totalComB;
            quanB += numComB; //for dailysalesreport
            SoldB = quanB * COMBO_B; //for dailysalesreport
            break;

        case'C':
            printf("  Enter Quantity > ");
            scanf("%d", &numComC);
            totalComC = numComC * COMBO_C;
            printf("  Combo C : %d @ RM18 = RM%.2f\n\n", numComC, totalComC);
            subTotal += totalComC;
            quanC += numComC; //for dailysalesreport
            SoldC = quanC * COMBO_C; //for dailysalesreport
            break;

        case'D':
            printf("  Enter Quantity > ");
            scanf("%d", &numComD);
            totalComD = numComD * COMBO_D;
            printf("  Combo D : %d @ RM24 = RM%.2f\n\n", numComD, totalComD);
            subTotal += totalComD;
            quanD += numComD; //for dailysalesreport
            SoldD = quanD * COMBO_D;  //for dailysalesreport
            break;

        case'Q':
            comboCharge += subTotal; //Total of all the combo selected

            tax = comboCharge * SST_RATE / 100;   //Calculate SST charge
            totalToPay = comboCharge + tax;       //Total amount with SST

            printf("            Combo Charges = RM %.2f\n", comboCharge);
            printf("            Add (10%%)SST  = RM %5.2f\n", tax);
            printf("            TOTAL TO PAY  = RM %.2f\n", totalToPay);

            printf(" Amount Paid   > RM ");  //Amount that customer paid
            scanf("%lf", &amountPaid);
            printf("            Amount Paid   = RM %.2f\n\n", amountPaid);

            if (amountPaid < totalToPay)
            {
                printf("Insufficient funds\n");
                printf("Enter amount again > RM ");
                scanf("%lf", &amountPaid);
                changeDue = amountPaid - totalToPay; //processing to change due
                printf("            Change Due    = RM %.2f\n", changeDue);
            }
            else
            {
                changeDue = amountPaid - totalToPay; //processing to change due
                printf("            Change Due    = RM %.2f\n", changeDue);
            }

            totalTax += tax; // for dailysalesreport

            printf("\nTHANK YOU FOR VISIT OUR RESTAURANT,HOPE CAN SEE U AGAIN! HAVE A NICE DAY!!!\n");
            break;

        default:
            printf("Invalid input,please select A,B,C,D for making order or Q to exit\n\n");

        }

    } while (toupper(selection) != 'Q');

        printf("Next customer? Y/N > ");
        scanf(" %c", &again);

        if (toupper(again) == 'Y')
        {
            menu();
            printf("  Customer No : %d\n", ++customer);
            selection = order();
        }
        else if (toupper(again) == 'N')
            dailysalesreport();
        else
        {
            printf("Invalid response,please select Y or N\n");
            printf("Next customer? Y/N > ");
            scanf("%c", &again);
        }

    system("pause");
    return 0;
}

//Function Definition
void logo(void)
{

    printf("                  ------=====----------------------=====------                          \n");
    printf("                     \\\/#\*****]|Jingex's Burgers|[*****#\/\\                          \n");
    printf("                  ------=====----------------------=====------                          \n");

}

void menu(void)
{

    printf("                                   <MENU>                          \n");
    printf("  Combo A > 1x Chicken SuperDeluxe Burger & 1x French Fries & 1x Drink\n  Price : RM10.00\n\n");
    printf("  Combo B > 1x Chicken SuperDeluxe Burger & 1x Onion Ring & 1x Drink \n  Price : RM15.00\n\n");
    printf("  Combo C > 1x Ultra Instinct Burger & 1x French Fries & 1x Drink\n  Price : RM18.00\n\n");
    printf("  Combo D > 1x Ultra Instinct Burger & 1x Onion Ring & 1x Drink\n  Price : RM24.00\n\n");

}

int order(void)
{
    //Local variable
    char selection;

    //Customer selection
    printf("  Combo A,B,C,D (Q = exit) > ");
    scanf(" %c", &selection);

    return selection;
}

int dailysalesreport(void)
{
    //local variable
    int totalQuan;
    double totalSales;

    //starting value
    totalCust = 0;

    //process
    totalCust += customer;
    totalQuan = quanA + quanB + quanC + quanD;
    totalSales = SoldA + SoldB + SoldC + SoldD;
    totalRM = totalSales + totalTax;

    //output
    printf("\nDAILY SALES REPORT\n\n");
    printf("Total Number of Customers = %d\n\n", totalCust);
    printf("Combo Sales For Today\n\n");
    printf("Combo        Quantity Sold        Sales Amount\n");
    printf("-------------------------------------------------\n");
    printf(" %-6c%14d%20.2f\n", 'A', quanA, SoldA);
    printf(" %-6c%14d%20.2f\n", 'B', quanB, SoldB);
    printf(" %-6c%14d%20.2f\n", 'C', quanC, SoldC);
    printf(" %-6c%14d%20.2f\n", 'D', quanD, SoldD);
    printf("=================================================\n");
    printf("%-6s%15d%20.2f\n", "TOTALS", totalQuan, totalSales);
    printf("\n");
    printf("               TOTAL SST charges  =  %.2f\n", totalTax);
    printf("               TOTAL RM collected = %.2f\n", totalRM);

    printf("\n");
    printf("THE END! HOPE TOMMOROW IS A BETTER DAY!\n");
    system("pause");
    return 0;
}