Vodacom cancellation failure

Cancelled my account in Jan 2019 and still being billed every month. Reason for cancelling because I was getting someone elses invoices and they simply could not fix it after numerous attempts. Cancelling alone saw me making at least 5 calls and calls were dropped yet no-one attempted to call me back even though they knew my number half way through the process. Now am trying again to go via one of the dead end numbers they display to query these debits, am getting absolutely no-where.