MTN LTE cancellation *****

Absolute terrible service when it comes to cancellation of a contract. I cancelled my contract on 30 Oct and MTN still debited by account in Nov and Dec. When I called today (5th of Dec) they said the initial cancellation was not processed correctly and gave an error. I already handed back the MTN LTE router on the 30 Oct at a MTN store. They cancelled the contract again today but now they do not want to reverse my last 2 debit orders because it wasn’t cancelled correctly at that point. I failed to understand why I should pay for a service that I cannot use since 30 Oct with no LTE router.