Incompetence at Vodacom

Since a change in contract in June 2020, I have been charged increased amounts each month, and each month a different amount( always higher than the contract agreement). Vodacom said they cannot refund me or seem to sort out my contract. I have 9 different references numbers and have called approximately 15 times to get it sorted. This seems an impossibility for every employer at Vodacom. Furthermore, on the 1st of each month my phone does not work outside Wi-Fi!! I want to cancel everything with Vodacom but they say I am liable to pay - pay for a contract that I have not signed and that they have faltered on 100%.