Thanks for the reply Rob!
I guess this was a one off and they got it resolved eventually.
I removed the NRV,s from the valve body earlier this morning so I will see if we now have a non sticking shower tomorrow morning. (one of the valves had a stuck plunger!)
If I still have an issue, I will...
Dear Lynnoakwood
I know this is an old thread but as I have exactly the same problem with another manufacturers shower product.
I would love to know what the resolution was for your problem.