Hi,
Preamble,
Shower in ensuite is a long way from hotwater system. Takes about 30 sec to get hot.
Problem is: we lose pressure (which alters temperature) when increasing either flow rate to hot or cold faucets?. sometimes a "clunk" is heard behind tap area.
We have to turn off both taps and slowly try to get an acceptable temp and flow rate.
Thanks in advance
saint53

What kind/type/brand of faucet is it ? It it shower or sink faucet ?

But in the interim: it sounds like you have loose washer on stem. Remove h/c stems, replace washers, reinstall.

Glad to be of help !