I have a LeFroy Brooks shower unit which has a thermostatic part which is attached to the wall and you simply turn the knob for hot and cold.
However a week ago, the knob just stopped turning. It is almost stuck and does not move at all. The problem with the unit is that it is quite sealed so I am not sure if anything can be done.
This is a link of the shower unit.
I have not opened it up but any advice would be great as I have not encountered this problem before.