Mtn ruin my life

On the 31st of July money was debited R782 from my account as per usual.But few days after I received an sms saying my account is in arrears than on the 15th they debited money R782 again of which I disputed because I didn’t understand why they debiting twice because usually they debit on the 31 of every month.On the 31 of August they debited R1500 something I disputed it than went to the store to make the payment of R783 on the 5th of September.Even on the 31st of September samething happend I disputed it and made the payment at the store on the 10th of October.I’ve been trying to solve this matter since August till now I’ve made various calls and went to the store but still I couldn’t get help.Now my contract ended in November I tried cancelling but they don’t want to cancel it because they say I owe.Now my balance is going up because they say I didn’t cancel my contract and they are refusing since August because they say I have to make the payment.Now they telling me I have to pay because my contract is still active.They have black listed and I don’t owe anything I’ve send my bank statement to various consultants but still no luck.Still they can’t give me a clear answer on which month am owning.Because in August when I called they said they didn’t receive any payment from me for July.But yesterday I went to the store again it does appear on the system.They don’t know which month they penalised me for and it’s affecting my credit score