potterton combi 80 pump stops when hot?

I have had same problem. It sounds like you may need new DHW/CH temp sensors; (potterton no:430011), as well as You may need a new pump if it has been damaged when jammed.
The DHW/CH thermostats may also need replacing, if the water is too hot.(nos:929562/929634).
I have used the 'Rated tradesmen' internet site to get reliable tradesmen in the past if you don't know a reliable heating engineer. Best of luck.

Jay
January 2008