Vodacom data

I had a 24 month data contract, cell no ***, with Vodacom. It expired on 31 August 2020. I cancelled the contract at the end of July 2020 as instructed by Vodacom. In spite of this I was still billed for September and October 2020. I made several calls to Vodacom and was assured that the matter would be rectified and refunded. I have today received an e-mail from them stating that I am now a pre-paid customer. I do not want this and just want my money back. I have the names of the customer service consultants I spoke to. Can you help, please?