dialers are dieing fast due to cheap broadband connections hitting the UK
the best option is these days would be
http://www.nochex.com
it Bills all UK debit cards with a paypal type setup
here is an example of the payment page
https://www.nochex.com/nochex.dll/ch...+Slots+Branded
the other option would be to bill by SMS but can be a little tricky to set up