My brother in law has a thermostatic shower bar that will not maintain set temperature and the guy who fitted it about 12 months ago doesn’t want to know about it and will not come to repair it even though he is not trying to get it done for free. Are the fittings from the shower bar to wall standard sizes and a universal fit as this one has fitting centres of 150mm, and he has asked if I would fit him a new one in its place. There is no name or anything on the one fitted so a change of shower bar may seem the easiest. Any info would be appreciated.