Again poor service from MTN

I've got 5 Top up contracts from Mtn signed for a fix amount for 24 months. From May my accounts increase and there are extra calls and data booked and billed on the account. The one account is only a 2 G data contract but there was calls booked up to R 256.00 on the R 99 fixed contract. The bills was paid by debit order every month. <br> <br> I just like to know how they can increase a contract fee if it was fixed and signed for for 24 months, From April I logged complaints about Mtn but up to now nobody from MTN has contacted me. If you try to contact the help line *** to leave a complaint, they just don't answer, So they just don't care but take my money every month. <br> <br> I would like somebody from MTN to call me so that we cab sort out all my problems because I just had enough of MTN. They will never ever get a good rating from me again.