Staff account making my life ****!

My staff account is active after I lefted the business. Yet I signed a form upon my last day , stating that my pension overs that amount in full. (As I was under the impression). A year later to find out my credit scoring is in red because people at Tfg can follow instructions. How can I owe on something that I don’t have. My card was taken from me. Also I signed a form where they need to cover that amount. Upon calling Tfg head office. They told me that these things happen and a lot of there EX staff are calling in and complaining about this. But do you honestly think this is right and lawful of them ?

Need someone to get back to me ASAP from the slc building or from insurance department.