I have a problem controlling the temparature in both the ensuite shower and the main bathroom. The water is either bolinig hot ot freezing cold. When the water is boiler hot and I try to adjust it to make it warm it just goes cold. Initially we thoguh the bolier was not producing cold hot water properly so we have the boler controls changed but water is being produced but the water tempatartue in the bathrooms seem to have a mind of their own. The shower in the ensuite is electric and the shower in the main bathroom is linked to the main taps. Help please

What brand and model numbers are your shower valves? Can you post pictures of the valves. Thanks

What are shower vavles. Sorry not very knowledgeable about this