I had a new shower installed over my bath, it been working fine however now there only seems to be warmish water coming out when the bath tap & any other taps are producing hot water.
The showers assisted by a pump & I've always had to lower the shower head when turning it on to make sure the power is OK. Holding it down you get slightly warmer water. I've undone the tube that connects the shower head & that's producing slightly warmer water.

The only recent thing is the water company have been doing work last week and produced an air block from the kitchen sink & now the water pressure is a little less.

Any clues?