Payment requested for a contract I do not have

I have cancelled my contract with Telkom in July 2017. Now I have been getting sms's from debt collectors about fees I need to pay for a contract I still have them. I have sent 5 emails already about clarity on the situation with proof of payment and the written cancellation approval. I have phoned Telkom to no avail. The lady informed me she has no record of my payments or any outstanding fees since the information was given to the debt collectors and it is my responsibility to provide Telkom with all the information they require. I have also informed the debt collectors of my proof of payment and cancellation, of which I received no reply. I have also informed my local Telkom shop of my situation, of which nothing was done. I cannot seem to get any information of head office on the internet.