I know redemption deals aren't everyone's cup of tea but if you are up for one e2save are regarded as one of the best companies for paying out. I've had a couple of redemption deals with them & never had a problem with payments.
HTC Wildfire on T-mobile 18 month contract @ £20per month
11 Months @ £1.99 by redemption = £198.11 cash back (5 payments of £39.62) over the 18 month duration of the contract, In effect this makes your line rental £8.99 per month. (£161.82 over 18 months)
Quidco & Top cashback are currently offering £46 for a contract taken out with e2save
£161.82 - £46 = £115.82
£115.82 / 18 months = £6.43pm
Make sure you cancel the 1 Month Free insurance and the 1 Month Free Gadget Helpline Support that you are forced to take out otherwise they will charge you £7.99 and £3.29 each per month, do that when you phone arrives.