in my homecountry there are many laws around rentalhouses and work to it
I our country we are still in stage you like it stay you don't like it leave. She is nice but just doesn't want to spend money for improvements.
Warm water "from city" should be 52'C warm. You need a termometer to 100'C. You may report it to spółdzelnia or administrator. This is a serious argument and they "usually" react very quickly. City heating system ends in basement and 99.99% works well. Problem lies in old or thin pipeline in building or they deliberately order 48'C to pay less for heat.