Vodacom cancellation nightmare

Vodacom continued to debit money from my account when I cancelled my contract on the 2nd of Nov 2020(contract was due to expire in December. I called the cancellations department numerous times requesting that they credit my account as I had cancelled my contract in Nov. No investigation was done to verify if really I had called to cancel. I was told the query was escalated to accounts department. Accounts department told me they will not be able to assist as the credit was invalid because an investigation was not done. It seems to me Vodacom does not want to take accountability on this matter as I keep being referred to different departments. This is not the first i experience something like this with vodacom. Please reimburse me what’s due to me. Please get the call recordings and do a thorough investigation as I will not be paying for someone else’s negligence