Sensitive shower - (in the control sense) - help

[pop80_uk]

Hi
Hoping one of you can help / explain something for us.
We have a hot water fed shower (basically a pump) triniton, around 7 month old. Working fine except for one point.

You only need to knock the temperature control knob at the position its at and the water either becomes freezing or scalding, so consequently we can only have it in the position shown below.

The slightest touch changes the water temperature hugely.

Any ideas?

Thanks

 

[picasso]

Could be a symptom of reversed hot and cold feeds.

 

[pop80_uk]

Could be a symptom of reversed hot and cold feeds.

Checked, its not that. ?

 

[Madrab]

Has it always been like that? Is it a Triton, (Trinitron was a TV by Sony ) what model is it?