Very Bad Service both Wonga.com and Nimble Collection Group

I settle my loan account with Wonga.com, after two weeks I ask them to close and remove the account from Credit Bureau, still with no successes, if I call Wonga.com they said I must call Nimble Collection Group, when I call Nimble Collection Group and send them emails of the paid up letter as a proof of payment they never clear the account till today they never help me. I'm strungling to clear this account from my credit report.