Landlord turning off Heat.

Woke up to the cold, it was 63 f. Checked the thermostat and the heat was turned off. Turned the heat back on and went back to bed. Landlord went to work before I did and I noticed they turned it off again. I took pictures and a video. I've lived there for about 4 years now, not really many issues that haven't been solved before. It has happened in the past and I've asked them to turn it on but I feel I shouldn't have to. My question would be what would be the best thing to do or who should I contact?