Does not want to cancel my contract, keeps on taking my money!

I have been trying my best to get rid of Telkom, but i simply cannot mange to do so. I had a LTE contract with them years back. I pay a little over R500 every month for them. I have cancelled the service(over the phone) way back... years back it has been cancelled, but i still get billed and if i dont pay they will blacklist me on the Credit Bureau. I have called numerous times! The one person tells me the contract was cancelled years back. The other tells me it is not cancelled, the next one tells me i have to do a trip of 150km to go cancel at an Telkom shop. I have been to that shop 3 times now, just to be told they are offline and wont be able to assist me!!!. Still every month Telkom is deducting the money from my bank??? What the hell must i do to get rid of them? Taking them on in court will accumulate enormous legal costs. I DO NOT KNOW WHAT TO DO WITH TELKOM??? In my life, i will NEVER ever again deal with Telkom! NEVER!!!