It is quite possible to write off credit card and loan debts if they are unenforceable, and quite a few of them are. They have to have been taken out before 1/4/07.
Cartel are one of the companies that may be able to help, however they do charge £495.00 upfront for the first case, a lower amount for subsequent cases and 25/30% at the back end.
This is a very expensive way to do it, there are better alternatives.