Blacklisted for Vodacom's Incompetence

So in 2019 I was immigrating to the UK, I phoned Vodacom and went into the shop to cancel my contract and pay what I owed. I asked on the phone and in the shop and confirmed with them that that was everything due. It took them a month and a half to cancel my contract and then they charged more money after I had left the country and did not have a bank account here. They have blacklisted me due to their incompetence. I had to come back to SA and I can't even get credit due to them blacklisting me. Vodacom is a joke of a company and they are very ***********. I will never use them again.