Sorry it was the diaphragm on the diverter he believed it to be originally however when he looked it wasn’t this it was a different part he said was causing the issue.
our boiler pressure is dropping to 0 even after having the blender valve replaced, paid £80. Maybe 2weeks ago. This was when our pressure was at 0 and only cold water was coming out. Now my water is going hot and cold every 15/20 seconds from the bath tap. Any ideas only moved in a month ago