In the statements "if(productnumber=0)" , i suppose you must have got a warning as i did. the test expression for the if statement is supposed to be a logical expression evaluating to true or false and not an assignment statement. i guess you meaned to write
"if(productnumber==0)" with 2 equal to signs.
sales[4][productNumber-1] += productTotal;
The above statement has been used once in each case of the switch statement with the switch variable "employeeNumber" and the only thing i noticed different in each case was in the idices of the 2d array sales. i guess this is what you must have meant
sales[employeeNumber-1][productNumber-1] += productTotal;
i didnt have time to go in to the logic of the program in too much detail but maybe sometimes correcting these if possible and reducing the number of switch statements to just a single line may help reduce the complexity and the size of the program to a large extent.
hope this solves your problem...:)