can not cancel expired contracts

i have 2 cellular contracts and 1 data. my cellphone contracts has expired but i cannot cancel it because my account is 2 months in arrears. i am aware that I'm liable for the arrears amount, however, i am still being billed monthly and the outstanding amount is just increasing and I'm being held liable for services I'm not using.enquiries was done at MTN Zevenwacht Mall( because i could not get through to customer care) and i was told if i settle the account and then cancel the contracts, my accumulated airtime and data will be lost when i migrate to pre-paid, alternatively i should use the accumulated airtime but make sure to do so before the statement date or i will be billed again and again and again.BOTTOM LINE I WILL LOSE MONEY. my appeal is for MTN to cancel the contracts and only arrange to pay what is owed and not continue to bill me. under no circumstances do i want to renew the contracts, in fact i have convinced everyone i know to leave this network and i will continue to do so.