All good advice Paul. 0900 numbers will cost you a minumum of a £1 a minute. But only if you connect. Sometimes they even have your name as a winner and when you claim your prize (at £1 per minute) - and 7 minutes later, after stating who has won the fab prizes, they tell you have won a two week holiday - but you have to pay the air fares! This scam has been running for quite a while - and you are out of pocket £7. They do it ALL day every day! Rich pickings eh?
The worst bit is that this one is LEGAL. But you can still complain.