I would just point out that this is a very rare occurence. If they had several thousand pounds worth of debt, the finance company will want to know how this money has been spent and what on. They will obviously check there recods.
If, for example, they have purchased a plasma tv and given it to a friend, it may be possible for the credit card company to have it repossessed from the friend.
If on the otherhand, all the payments have gone on alcohol and betting, then it wil be just a write off.