One more thing, beware of stupid arguments:

"You'll have to change your number!" - it that really a big deal? How many free texts do you get? (Enough to send all your friends a text and let them save your number?) Do you regularly see most people you phone? What about e-mail?

"Basically to cancel the contract it'll cost you £300, if you take this pay as you go phone at £50, unlock the phone at £40 and put your old sim-card in it'll only cost you £90! Much cheaper!) - Absolutely! If it's a matter of finding £300 today or £90 who wouldn't go with £90? But you're still on the same tarriff. 10 months at £100+ phone bills, plus your £300 is a lot dearer than £300.00 plus a new contract at £30 that gives you cross network minutes and lowers your bill to £15 a month!

Take your last 2 bills, note down how many texts you sent, how many calls to each network (if you know!) - divide it by 2 (to give you monthly average) and take that with you when you go shopping or look online.