My trusty 2 year old Siemens C45 is a bit worse for wear, although it still does everything I need of it (provided its battery hasn't run out yet!

), but I'm thinking of a replacement.
The only things I'd like from a new phone that the C45 doesnt give me are longer texts, good battery life, and faster WAP. Other than that I just want a reliable and hardwearing phone. Not bothered about cameras, colour screens, media messages, etc - although I suppose it's something to talk about in the pub
Want to continue to use my BT Cellnet Genie pay as you go sim as it's a better deal than its replacement O2 Online, and meets my requirements perfectly. Not quite sure what it would do about GPRS charging though, currently I get 300 free WAP minutes.
I will not touch a Nokia as they're pants in my experience. Same for Samsung and Panasonic! Another Siemens or a SonyEricsson seem to be my options then. Budget of £100.
Current ideas include:
Siemens M50 from my-siemens.com, was £42 but they've put it up to £60
Siemens C60, was £80 on Carphonewarehouse but it's vanished from their website today.
Siemens MC60 for £99 on TMobile, are they unlocked/unlockable though?
Any ideas folks?
Many thanks,
Ben