I have a thermostatic bar shower which has been plumbed in with the hot water feed on the right and the cold on the left. The shower was OK, but could never get a cool shower. However, recently the temperature is so hot I cannot use it. The temperature will not go down. Is this because of the way it has been plumbed in? All the pipe work is behind tiles now.

What's the brand name or your shower valve? Back to you. Tom