Cell C cancellation department

I have a contract with Cell C which I tried to cancel on the 1st of December 2020 and the lady that I spoke to told me that I need to serve the 30 days and they must also debit on the 25th since I was already credited with Data for that month.

Fast forward a month later, the contract is still active and Cell C wants to debit me. I phoned the cancellation department on the 18th of January 2021 and they tell me that they don't have records of me calling to cancel.

This is absolutely unacceptable and bad service and as a client I am very unhappy with the service I received.