Wonga claims i owe money i never took.

Wonga has been the worst service providers i owed then and paid. Now they keep sending emails by their lawyers claiming i owe amounts i don't even know about. Where do i go to report this because my credit score is getting worse over money i paid on the 19th of July already. I sent proof of payment more than 5 times to them n lawyers but still they haven't cleared my debt instead they say i owe them more. I have the settlement letter.

Wonga has the most disgusting service, whn you call they don't even pick up.