I'm living in a completely new building that was just finished this summer, and have consistently been experiencing water temperature problems. For some reason, the water temperature has never been hot enough since I moved in in August, and it's just been getting worse as the weather gets colder. I set the knob to as high as it will go and it is still not nearly warm enough. I'm not saying that absolutely freezing water is coming out; it's heated water, but it's not hot water. I am not trying to scald my skin off -- I would just like to take a shower and not come out shivering.
I spoke to the accommodation office about it and they said "yeah, we've been hearing that from some people; we'll take a look at the --" (I'm not sure what it was; the hydrostatic valve or something) -- "outside your room and see if that will help". Apparently it was then set to as high as it should go (55˚c/130˚F), but the shower just doesn't get nearly that hot.
I Googled extensively for answers and didn't really find advice for people who didn't have control over their own water heater. A common problem people seem to have is that their water temperature or pressure fluctuates wildly; mine doesn't. The pressure is fine, and the temperature just wavers between wait-this-is-a-bit-hotter-just-a-little-more-would-be-good and just-kidding-I-only-did-that-to-get-your-hopes-up.
Another possibly important thing to note is that my bathroom sink can indeed get scalding, so I'm guessing it isn't a problem with the hot water supply to the flat itself.
I know nothing about showers or plumbing but I want to go to them as informed as possible and suggest things, because it seems a level of incompetence that this cannot be fixed, or that this is a problem in a new building. The office told me that they had gotten "over a dozen" complaints about it, so it's definitely not just me.
What could be causing a shower to not put out hot water when the sink clearly can?
Update: After trying the mixing valve and getting the admin to come try and fix it many times, to no avail, the only thing that would help was running the cold water in the sink at the same time as taking a shower. Which is an unreserved waste of water but there seemed to be no other solution.