Bad Customer Service and Data *****ing

I do not understand when MTN says data will expire on a certain it has to be at 00:00:01 and not at 11:59 pm on same day. I had 15+gig data expiring on the 28th of february and when I checked in the morning my balance was already on zero. When I called the call centre a rude female agent said I should call ICASA and not MTN since they do not make the rules. I signed up a contract with MTN and not ICASA and they never explained that data expires at one second past midnight of the previous day when taking the contract. I then asked for her supervisor and she made me hold for more than 30 mins and I could hear people talking in the background till she dropped the phone. Such bad customer service is unacceptable at all.