We're really sorry about the past weeks site performance issues...
Our current host just wasn't up to scratch and its been causing the site to go down every few hours, for anything between a few minutes and few hours at worst. It was down to a scripting issue they couldn't handle properly and the server wouldn't scale as needed.
Its actually a sign of us growing fast, and we decided to take the plunge and completely move the site to Rackspace, which is a much bigger host and also has automatic scaling to handle traffic increases.
We made this move yesterday and everything is fine now - much more stable.
If you've had any problems with the site, or couldn't order, we're sorry for the inconvenience, this won't be happening again.
Onwards & upwards!