Unauthorised removal of data

My daughter has phone which is on contract via Altec autopage, due to the high cost of data i changed the contract to a top up, so when her data is finished i can top it up, For the past - 4 months i purchase her 1 Gb of data from MTN which gives you 1 extra GB free and is valid for sixty days, after - 12 days she receives a SMS from MTN stating her date will expire in 2 days, on around day 14 all her remaining data gets removed.<br> I went to a local MTN shop who said that as the phone is on contract they have no access to her phone no, and that we must use my daughters phone to phone MTN so they could pick up the no at head office and that would enable them to see why they were removing her data, we have tried numerous times to get through to MTN and hold on for over an hour without anyone answering, I'm now in a dilemma as she needs the data for studying and I cannot afford to purchase her Data every fortnight, the cell no I have put down is not my daughters but my own