Extended my Contract without my consent or records

I had a 2year contract with MTN after contract ended MTN continued to take the debit orders from my account upon going to their store in Sandton i was informed it was a 3year contract. I argued with them that for them to give me the two year contract it was an issue because my work permit was expiring within 2years however they agreed to give me the 2year contract hence my passport was only expiring in 30months. I demanded to see the 3year contract that they were claiming i had signed but MTN does not have records of my contract. I wrote to them and tried their call centre who kept referring my query to early cancellation department. Until today they haven’t resolved this issue yet they are taking money from my bank account. I do not want to tarnish my credit score by stopping the debit order from my bank. MTN please rectify this issue asap and all my monies refund bank into my bank account. I cant wait to get this resolved and move to Vodacom. Unhappy client