Shower screeching doing my head in. Help!!

[onanothertrain]

My bar mixer shower has started screeching when the washing machine is filling, toilet is flushed or cold tap run. It also drips. It stops if the hot tap is run but obviously I can't leave it on. It also stops if the shower is on. It seems that it slips from being in the off position. I'm struggling to get a plumber and Google suggests it might need a new flow control cartridge which looks quite easy to replace. Has anyone had a similar problem and have any words of wisdom? I've shut off the water to the shower to stop myself going out of my mind 😭

for some reason, bar showers are quite cheap and not durable. However they are quite easy to remove and replace.

Do you know the make and model of yours?

Post a pic please

It's a triton tesla thermostatic bar mixer shower. Luckily due to being installed on the cheap none of the pipework is tiled in.