O2 coverage dropping off?

Firstly, a rant. I am up in the NE of Scotland and the O2 service seems to be getting worse and worse. I have had no service for over a week now in my home town.
The excuse was "We know there is a fault but we don't know what it is".

Secondly, a question. Can you cancel mid contract and how long do you have to wait before you can do this?