Terrible customer service

My father was late with his June Payment, as soon as he realised, he made the payment, his email was interrupted but it then resumed and worked normally until the end of August when his account was cancelled. His account is in credit to the extent that he shouldn't have to pay again before March 2026. I have been trying for 10 days to speak to someone to sort it out - without success. Not on their help line nor live chat. They have the WORST customer service of any company I have ever dealt with.