well if your on o2 you can upgrade to a 16gb iphone 4s on a £36 a month contract and get the phone for free untill the 31st october.
http://www.o2.co.uk/iphone/iphonetariffs/
i'm umm ing and arrr ing, but i dont like the fact that with o2 you now no longer get any data included, you have to pay £6 for 500mb of data or £10 for 1gb of data, ie: browsing web, emails, apps that connect to the web,
when i got my iphone 3gs i got unlimited data, thats the only reason i havnt upgraded my phone yet, i would have to pay £6 more a month for less data, yet i would get more minutes and unlimited text, but i dont use the text and call time i have now, so to me it would be a downgrade that i would have to pay extra for, not an upgrade
i might get the 300 mins one at £26 a month and £6 for net data and £269 for phone