Hi, thanks, that was going to be my next step but I'd heard mixed reviews about how good they are. I've opened a ticket with them now so will post again when they reply.
I've just rang HTC and spoken to a guy who said that my only option really is to send my phone off to them for repairs. He said that it sounds like a software issue and that they would reinstall the software on the phone which should fix it. I'm reluctant to send it away however as I'm not sure I can be without my phone and I'm also concerned that they'd charge me a lot to do it. Is there any way that I could reinstall the software myself? I know it's risky but I'm willing to give it a try if it means not sending the phone away. Thanks for your help