Sony Ericsson C905 Contract Phone Cancellation?

[save_us_king]

I renewed my contract in june from a sonyericsson w760 to a sonyericsson c905 and it runs out november 2010 but i keep having problems with the mobile it keeps freezing getting stuck on no network coverage and its pissing me off

So im wondering could i cancel the contract or if i upgrade could they offer me a new mobile