I am having similar angst to dave chimaera over mobile phone upgrades.
Summarises as:
I think I want an Nokia E71
Can't get that as an upgrade on T-Mobile
Available on 3
Also available as a new contract through expansys but I'm not sure if I can do that as an existing T-Mobile and if there is any chance of keeping my number.
Several independents have said they can't do that phone on T-Mobile.
Apparantly they get this a lot and their suggestion is to get a PAYG sim on a different network and PAC your number from T-Mobile to that, and then you can PAC it back over to the new contract. Its a bit of a faff and will take a couple of days per hope but will work *shrugs*
If it works I think I have an Orange PAYG sim somewhere ;->
Definitely leaning that way though.