Vodacom *****ing from subscribers

Vodacom has been *****ing money from me for years, they can never explain their exorbitant invoice amounts and I have found that they have numerously charged me for things that I haven't signed up for and then had to refund me. I have cancelled my subscription with them at the end of 2021, and they are still charging me. My contracts came to an end and I did not renew it, as I was planning to relocate to Germany, which i have done. They have emailed my an enormous invoice and I refuse to pay it as I had cancelled my service plus did not renew my contract.