In reply to ashaw:
This has been covered by various consumer programs. The clearing system only works on account number and sort code. If you get the name wrong, that makes no difference. If you pay into the wrong account then you can hope that that person will kindly return the money, but there is no guarantee and I believe there is no recourse either.
I guess you should be ok because world challenge (whoever they are) have not fulfilled their side of a contract by paying you. They paid someone else by accident - their problem.