Cell C Stop de*****ing us when contracts ended

Please note the contract I had with Cell C ended in July2021 , I went to the store to cancel around mid June and was advised to contact 084135 , I called and was advised that I should've called 30days prior if i wanted the contract to end the day of the expiry date which was end of July2021, therefore my account will be billed at on the 01 August 2021 since I called mid June2021. I requested the contract to be cancelled and agreed to be billed on 01 August2021. I only realized this month October that Cell C is still billing my account but the amount has changed to ZAR 179.00 which I was never advised of nor agreed to those changes. I called again 084135 on 01 Oct 021 and spoke to a lady called Lerato. I explained my situation and she was sympathetic but couldn't assist. she transferred me to the cancellation department but the line got cut off before I could speak to anyone. I don't want to continue with the contract, please cancel this thing asap!!!!!!! Stop de*****ing your loyal customers