Pathetic service

I called the Telkom call centre and explained to the agent that I want to cancel my contract because when I took it we agreed that I was going to Pay R240 every month. Next thing I knew I was paying around R500 monthly. I then called in to tell them to cap it and ut the limit to zero,which they claimed to have done but I was still billed the same ridiculous amounts. I then told them I want to cancel my contract. The agent sent me a cancellation form which I filled in and returned on the 04th of Dec. I called to confirm if they received it ,they said yes and my contract will be cancelled in 21 days.I then called them today and they said they never received any form .I resent the previous one and they said I must wait another 21 days. At the same time they will continue billing these ridiculous amounts.Please close the stupid contract and I want nothing more to do with Telkom.