Affecting my Credit applications

I am in the process of applying for a homeloan and was declined by the bank due to the following reason: “client benefited from ********** Wonga funds”. I would like to understand what this means as I haven’t used my Wonga account in over 3 years; and this has now dented my credit record. I would want to rectify the situation as soon as possible but clearly I am not winning. I think best advise received so far is to go via the ombudsman.