Pathetic Service

I was a previous employee at TFG and left at the 31 March 2023. I use to have a staff account with a mobile contract linked to it. When I resigned the staff account had to be paid up in full and closed with immediate effect on the last day of employ. I am extremely annoyed with TFG mobile as they have not ended this contract that was linked to my staff account and has blocked my number as a result that I am apparently in arrears. I tried called but can never get through and sent numerous emails but no response. I need this mess sorted and this account closed, which should have automatically been done when I left. As far as I know I do not have any staff accounts with TFG and therefore should not be in arrears and owe TFG zero as this account was fully settled at the end of March. This mess is affecting my credit rating. Please can someone assist to sort this out.