unlucky mate I work for o2, could have arranged something. If you're up for renewal in May, call them and tell them that you want to leave due to the new price increase and you've been offered a better deal from o2 on a family discount 30%. Say you don't want to but cash is tight.
Thay have a "retention" team that will be able to offer you a better deal I've also heard because they're losing a lot of customers despite them having 4G, they are offering decent deals.
You have to bare in mind, stupid deals don't happen anymore, costs of the handset and the deals you get now compared to 4 years ago are worlds apart.
Who would have thought you could get unlimited everything for around £26 a month?
The handset is the cost, on o2 unlimited on and on 37 the Z cost 49.99 when orange get it you'll be looking at around the same. normally the save deal would right off the cost or knock the monthly down to 32. Thats about as good as it gets because the deals are so rich people tend to stay in the allowance.
How much you looking to pay a month? To be honest, I would stay away from the T, its out dated and was when it was released mid range phones have the same spec 1.5 dualcore 1GB ram. Quad is the way forward and don't forget 2 years is a long time to stay on a dualcore phone while all the new flagships are quad core.
You could even look at buying a Chinese phone. Google Newman N2, cost around 190 the phone i've ordered which makes the S3 look like a mid range, is the Jiayu G4 advance/pro. They do 2 versions the standard G4 has 1.2 quad core 1gb ram, Retina screen, 312PPI, IPS screen, Corning II Gorilla Glass, 13MP camera and 3.2mp front facing 16gb. the pro same but 2gb ram and 32gig. I've just ordered the pro for $250 with postage works out about £152 no joke