Vodacom damaged my credit score after contract cancellation

To make a long story short. I sent an email to cancel my contract during October 2020 but the debits kept coming. Another email in November 2020 but up until the end of April 2021 the debits continued. Spoke to cancelations Ref number ***, was guaranteed that my money would be paid back. Nothing, and it's May 2021 already. To make matters worse, my credit score came down last month because Vodacom listed me as missing payments. Tried mailing the retention.cancellations again but mail came back undelivered, address not found. Can't speak to an agent either. This is not my preferred reaction but I see it as a last resort. I need my credit profile fixed before the end of May. PLEASE HELP an EX-LOYAL CUSTOMER that never missed a payment before