My mate Joe overstayed his welcome and received a shock "fine" from CPS for sleeping on the services
well if you do and stay more than 2 hours then you will get an "official looking" demand for £50 or more .
Dont panic-ignore it ...its an invoice not a penalty charge and is unenforceable in court
They will send you numerous threatening letters each sounding more official than the 1st one.
Ignore it !
do not even reply . There are many forums discussing this issue but the best one is this watchdog interview with a solicitor .
Take a look then decide if your still willing to pay up
http://www.vwt4forum.co.uk/showthread.php?t=176686&page=2