Cancelled my contract and MTN is still charging me penalties

As i emmigrated to Australia I paid R230 to cancel my contract in August 2019. However the contract was never cancelled, I sent numerous emails but no reaction from MTN. Now I have been handed over to debt collectors to pay a certain amount which according to MTN is outstanding!I do not have a copy of the payment made as I lost nearly all of my documents which was send by sea. I asked for back copies of my statements, nothing has been received yet