Hi Fabi, Do you know where the water stockcock is to the whole property? (rather than just focusing on the bath tap) Camden would be responsible for locating the former (because that’s where their responsibilities end), not the latter.
I know there was talk of setting up a TRA in your neighbourhood, but don’t know what happened; it may be that other neighbours may also have some experience if you send them a comment via this (admittedly old) website to “connect” with them: https://stsilasnorth.wordpress.com/2014/11/30/first-agm-of-st-silas-north-tra/
Other people may have more useful suggestions!
p.s. I know my stop cock for the property is underneath the kitchen sink, but I somehow suspect that every block may have their stop cocks in different places.