Unauthorised contract

Good day Two years ago I got a Vodacom contract at Game for my Mother and sister, two phones for R399 and I've been paying the contract from my bank account. The contract ended in January 2025. I got a phone call from an agent on the 30th November 2024 to upgrade the contract but I refuses , just wanting to get the contract over with. Unfortunately I noticed a debit order going off in February (R445) and March( R389) 2025 and I called the customer service line to query it on the 18th March 2025. The agent let me know that I had apparently opened another 2 year contract which I absolutely did not do and I told him so ,asking him to please cancel it. Unfortunately he told me he couldn't, he could only lower the instalment then I could cancel after 3 months. I also asked him to log an investigation and get back to me, he said it would take 72 hours . I still haven't gotten any feedback to this day.