MTN the pirates of communication

Our contract with Mtn ended 8 and 9 September 2022. Mtn deducted from our account almost 3.5 times the contracted amount on the 26th. We queried this with them and they said it is because we did not upgrade the contract. We tried to cancel mtn with them and they refused and insisted they will charge us. They even went as far as to try and get a debit order for a exorbitant amount of almost 26 times the contracted amount per month from our bank account on the 28th. When we queried this they said it was for credit. Mtn is supposed to be the best brand, they supposed to look after their clients, yet they seem to hold you ransom. At no time has anyone contacted us and said if you don't upgrade the following will happen and you will be charged more than agreed amount in the contract. At no time have they given us a copy of the contract or even the terms and conditions. PLEASE BE AWARE OF THEIR BUSINESS ETHICS, as they will stop at nothing to milk you dry.