[Closed] Unlocking a Nokia 2700...help!

Just bought a Nokia 2700 on Tesco, need to unlock it so it can replace my broken phone. (£30 cheaper on Tesco network otherwise I'd have got it on the correct network!)

It appears its a more recent model...I've found a couple of websites that say they can unlock it or money back in seven days, but most say they don't support it. One was ready to take my money, then I checked the T&C's and as its not on the supported list, they'll just tell me it can't be unlocked in return for my £5.99!

Don't want to be sitting around for seven days with no phone then find a refund sitting in my account and back where I started!

Thanks for any help...