Robinet de douche classique avec valve brute 1323

I bought this a month ago and now we can not adjust the water temp. We have watched the videos and nothing is working.

I had professional to install this faucet in summer time. It was fine till the brutal winter hit. The hot water in other areas of my house is hot, but not the shower room. After taking shower , I had to put on robe right away, for the water was lukewarm.

Spent the money, liked the style, installed by licensed contractor. Realized the temperature regulator feature is basically worthless. With HW heater stacking a common occurrence, it's really not a viable feature. Now that it started leaking 18 months later, I'm replacing it. Perhaps a bit "over-engineered". I like Delta, will stick with them, but def not this model.

The trim looks nice but the valve to protect the water temperature from fluctuating does not allow the shower to heat up to the temperature of our other shower. This forces us to increase the temperature of the entire house water increasing our electrical bill just to get hot showers. Plus now our other shower and faucets are dangerously hot.

I bought a new home with this product installed in the Master Shower. I find the water flow to be weak. Is there a way to increase this? What domestic water pressure is needed to provide adequate flow to the shower head?