This sounds like Xtraview (Channel 36) Up until recently, Xtraview carried a selection of programming from a number of different subscription channels. (e.g. it carried programmes from the Cartoon Network around teatime, a couple of hours of UKTV Gold mid-evening, plus programmes from Discovery (& other channels as well) at different times of the day). So, if you decided to watch Xtraview, you didn't get a choice of several programmes - you had to watch the programme from whichever subscription channel they were relaying at that time of day.
To watch the Xtraview programs cost �1 per day. Pressing the red button on the handset brought up a phone number which viewers rang with a credit/debit card number. The viewer was provided with an access code which they entered via their handset - this unlocked the programming for one day only.
Xtraview (in the format described above) never really caught on. If you go to Channel 36 now, all you'll get is a message saying that the system is currently being upgraded.
Chris