Such bad customer help

I phoned Vodacom to cancel my contract with them. It was a premature cancellation so they said I would have to pay the remaining 3 months off. So I agreed to do so, they sent me a form also to fill in and send back with other required documents. This all took place on the 5 December 2017. I made the payment that same day and forwarded the documents the following day the 6 December 2017. I phone in weekly and kept getting the same answer it’s being processed and why sir do you wanna cancel. To only find out after I phone in yesterday the 18 December 2017 that nothing has been done and that I have to send all the documents again. I did all this so I can ensure I won’t be debited again for this month. My payment reflected on there side but nothing was done about it. I know that for all there time wasting and mess arounds they gonna debut me again and I will say I had proof but I am gonna battle to get my money back if they do debit me. I still have had no feed back and left in the dark.