******* vodacom cancellation conduct

I phoned Vodacom to cancel a data contract. I eventually got through to someone and they let me know what I should do. I followed their instructions which I documented and proceeded to follow up for two months to request confirmation of the cancellation instruction. This was a year ago - last week I was informed that they had handed my account over to debt collection which was the first I had heard from them. Again when I called them it was almost impossible to get through to someone and when I did they said the cancellation was noted on their system but had never been executed, and there was nothing they could do. I called the lawyers and they asked for a contract to confirm cancellation (which they had never sent). I'm not sure where to go from here! I could pay the amount but it does not seem right when there is proof of cancellation both in my email and on their system. There is also the impact on my credit rating.