Cancelled contract

My contract was due to end on the 31/12/2020. I went into the store to cancel my contract and was told to phone 135. After numerous attempts I couldn't get through. I emailed *** and was helped by Renall. Renall stated I will still be billed for the last invoice and the contract will be cancelled when the date is reached. I also told Renall that I want my number to go to prepaid. Today I received a call from an agent trying to get me to upgrade. I was told by the agent that my contract is still active and on a SIM only contract. I did NOT authorise this. I was told to contact 135 and held for 29 minutes with no answer again. How is it that I get inundated with calls from you when my upgrade is due, and I tell every agent I am going to cancel and they will make 'a note of it', but when I need actual assistance no one is available. Your customer service is disgusting, and one of the many reasons I am cancelling. Cancel my contract and send proof that it is cancelled and that no one else from MTN will contact me again. I am in the process of applying for a contract elsewhere and this situation is just delaying it further.