Remove debt on my credit check.

Hello, My Total Sport account was handed over to Norman Bissett & associates group i settled that amount, but on credit check it's still appearing when i try to contact them their lines are very bad they end p hanging up, they don't respond to my emails, I don't know what to do anymore more, in order for this to be removed on my credit check because it's affecting my score. Here is my Reference Number 2TFG48739.