Depleting data

I signed up for a 2 year promotional contract which gives me 1.2Gigs of data a month. I get given all my data, airtime and sms on the 14th of every month but for some unknown reason someone at MTN stipulated that my data must expire on the 29th of every month. Therefore I only have 15 days to use my promotional data before I have to repurchase it?????<br> I have tried on 6 occasions to sort this out with the call centre but no one know how to deal with it or can sort it out. I was unable to ever get some clarification as every time I was cut off and not one agent ever called me back.....Disgusting!!!! I hope management never gave the agents a wage increase after their 3 month strike, the way I see it not one of them deserve to be hired.