Vodacom does not want to cancel contracts and don’t even give a reference number for canceling

I have been unsuccessfully trying to cancel two data contract lines with Vodacom for 2 months. I phoned last week and spoke to the consultant who gave me the same line, I am waiting for a reference number and will call by the end of the day. And never did. They continue to bill me even though I have communicated to them more than once.