Claiming outstanding amount owed on cancelled cont

Cell C called me to claim that I owe them money. I cancelled my contract with them more than 6 years ago and at that time any outstanding money was paid. I have since not received any statements or any correspondence from them that the contract is still on going or even that there is money owed until today. This sim card was also cut up immediately after the contract was cancelled. Call center could even give me any details regarding the supposed amount that is owed.<br> <br> I also know of at least three other people who have encountered the same problem. Did doesn't seem that Cell C cancels their contracts properly on their system and then years later wants payment for something that was never used.