Credit record tarnished!!!!!😡😡😡😡

I had a contract with Flexi Access for 5 years. My contract came to an end in August 2024. I emailed them and communicated with a guy called Warren. Warren informed me that my contract was canceled and my last debit order was 1st August 2024. I reviewed my credit report and saw that this particular company had flagged my account, showing that I was in arrears from September 2024 until February 2025. Do note that my contract ended in August 2024. No one ever communicated, and this is horrible, according to my credit record. One works so hard to maintain a good credit record than this company wants tarnish it due to their negligence. I need an answer!