Ordered to replace a faulty actuator. Came quickly and was new as advertised. Saved me having to replace a whole valve,thermostat.tank thermostat and control box which are obsolete. Then the cost and trouble of getting a plumber to do the job this close to Christmas.
Replacement Actuator is a direct replacement for an existing valve of the same type very easy to replace only requiring a screwdriver to unclip the existing valve. The only down side is they are no longer available from the manufacture so if i have problems in the future i will probably have to look at replacing the control system completely changing the complete valve and all controls.
By heating packed up so done a bit of research on the internet.
The actuator seemed like the problem. Purchased it, arrived early and took 2 minutes to fit problem solved!!