we have our system running but our system needs to be modified because we did something wrong...we are doing an "Internet monitoring System" in our school library where the user can only access the internet 1hr a day, and he/she cannot use the internet within that day if he couldn't buy a time on a serve...every students should only have 20hrs time usage per semester...our problem is every day their 20hrs is being reduced in 1hr.. the rule is the time per semester which is 20hrs that is given to the students was reduced 1hr only if he uses the internet..but our system is reducing their 1hr every day...please help us..our final defense is on wed.

So you aren't logging when the user's use the Internet? Your reduction function run once a day and check the log for who has actually logged in - it sounds like your logic is missing a very important step...