Theft - Telkom ignores ongoing requests to downgrade expired phone contract to pay-as-you-go

My husband took out a phone contract with Telkom for me (I am the main user and the contract is in his name). The two-year contract expired earlier this year and we chose not to renew or upgrade - we asked for it to be downgraded to pay-as-you-go. We went into a Telkom store on 13 May 2017 and gave them the documents they requested and filled in a cancellation form. We were told it would take 22 working days to cancel. Since then we have gone in store and emailed multiple times and we have resubmitted forms each time, only to be told to start the process again and that it will take a further 22 working days each time. No one ever gets back to us and we just keep getting billed for a contract we do not want. This is theft. We also received very poor customer service when we first took this phone out and have been waiting 2 years for this wretched contract to finish. Telkom has proven inefficient and *********** as a company for as long as I have known them and to try and cancel a contract with them is near impossible.