Airtime gone the next day!

This have been happening for a while now. Every time I recharge my airtime, I'll go to bed having some balance. I'm not talking about the WOW bonus thing here. I somehow think is the one that brought up this problem anyway. Only the next day, my airtime is zero-zero. I mean REALLY now?...<br> MTN always finds a way to excuse themselves either-way! I made a call just now to inquire about this matter on Customer Service. And I was informed that I should wait for 24 hours. <br> <br> MTN, is about time you take your customers complains serious, and do something about your a problem, than looking for an excuse to bag you up. We're not ***s to milk cash from. I know two people who complained about the same issue. And I'm sure there has been a lot complaining of the same issue. And what ever you did was simply finding an excuse.