Bayport not clearing paid up debt

I have been paying Bayport every month with a debit order but it is old debt that I have been catching up. It was still showing om my credit report and Bayport said that I need to pay the outstanding amount for my credit to be corrected. I paid the outstanding amount about 2 months back and it still show on my credit score. I have called more than once but the issue has nit been resolved.