Vodacom did not cancel my contract, they messing up my credit record

Vodacom have not Cancelled my contract aven after sending them all the required documents, and now they are ruining my credit record because they say i still owe them. I have called Vodacom several times over the past 3 months and i always get the same response that they have received my cancellation documents and they don't understand why the contract has not been cancelled, my request has been escalated and should be resolved within 48 hours.

The only option i have left with is to report them to the ombudsman