“Being told to leave your window open is ridiculous, it’s frosty here today”
So you open the window and close the door. We do this all the time.
OP just buy some mould remover spray and stand on a chair to spray it on the ceiling. It is your responsibility to try and keep the bathroom mould free if the problem is caused by condensation from within your house. Breathing in mould spores is bad for you, and it only takes seconds to spray the ceiling with mould remover. If you ask the landlord to do it he will think you are taking the piss.
“For some reason I have humongous amounts of condensation this morning,”
And you haven’t worked out why Firesuit?
Every house or flat needs ventilation. Modern housing with draft excluders and double glazing will be prone to damp if there is nowhere for it to go. It is basic science. The windows in our house have trickle vents so we don’t have a damp problem at all. Both bathrooms have extractor fans, as does the kitchen, and if I want to dry washing indoors I put the airer in the bathroom with a dehumidifier and close the door.
Most people seem to underestimate how much water is in wet washing. I usually tumble dry if it isn’t dry enough to hang out on the line, and when I empty the condenser there are several pints of water in the tank. If you dry the washing indoors with windows closed where do you imagine the water goes?