*****ing money

It seem that MTN does not know how to Cancel a Contract. I bought a MNT home internet router. After returning the hardware and cancelling the contract (Cancellation request was done on 16 July 2023) I am still being billed for this contract. After numerous attempts nothing has changed? No one from MTN is contacting me to refund the money they are steeling from me. I would never advise anyone to use MTN as a service provider. If anyone has advise on resolving my issue please advise.