If you go on the BT website, the cheapest you can get unlimited broadband is £28 (with their phone deal- package 3), or £25.60 for just the broadband.
I didn't want a complex package, all I wanted was a basic phone line with unlimited internet access. Seemed simple enough, but had no way of selecting this without extortionate charges on the BT website (and the little person on the chat told me it was that or nothing). When I called to explain what I wanted (and that I could get the unlimited bit for £15 from Sky), they said they had other deals that weren't on their website.
The package they offered me, tailored to my needs is as follows:-
Unlimited Broadband, with access to wifi broadband out and about.
Free weekend AND evening calls to landlines etc (with caller ID, answering machine etc)
Free BT home hub AND telephone.
All of this is only £10, and is on a 18 month contract. They said it was a special offer (and is usually £23), so if you want something like this, I'd call quick.
I also paid my 12 month line rental up front and saved quite a few pounds by doing this also. It essentially means all you are paying out monthly is £10, which is a fantastic deal.
The next cheapest I could find was through Sky, and it didn't offer all the other little extras.
After being bitterly disappointed by Virgin Media (and nearly ending up in court), having rubbish service from TalkTalk, being cut off and messed about by Sky, and having a nightmare on AOL, this was so much easier to set up, and seems a lot better deal in comparison to everywhere else.