radeng,
I really think you have the wrong end of the stick here! The Orange website shows the only dial-up service as PAYG,
only pay for what you use
* 2p a minute all weekend (Friday 6pm – Monday 6am)
* 4p a minute weekday evenings (6pm – 6am)
* 5p a minute weekday daytime (6am – 6pm)
Perhaps they are misunderstanding your question, and telling you that IN ADDITION to broadband for £11.50/m, you can have dial-up access at a PAYG rate?
Or perhaps you are confusing phone call charges in the phone & broadband package they are offering with dial-up charges?
Otherwise you (or they) are not making sense!
I suggest you visit the Orange website to get a better understanding of their products, services and charges.
And then compare to others!
If you are in a cable area then you have another alternative.
Of course if you are many miles from a BT exchange and cannot get DSL, then perhaps you are over a barrel!
SD