How can the heat be controlled without a thermostat

I live in a apartment, there are two King thermostats in my place, they are old model
S22 125/250/277 VAC
22 AMP SINGLE POLE
LR 27080
E 47273
The heat was on at level 55 at any room temperature even in hot summer. Recently I don't know what the maintenance men did, they made the heaters work incorrectly. The heat in both rooms is only at 65 or higher levels, lower than that the heater don't work, they are off completely. I complained about that, they said the thermostats were sensitive with the room temperature, if the room temperature was higher than that level, the heat would be off. It not true, the thermostats did not work like that way before, I could turn them on in hot summer. They were quiet, no more answer.

They did the same thing with the stove, the grids are sometime extremely hot at low level. I requested to fix this problem twice, but it still happens rarely.

Can you please tell me how they can control the heat from outside, and how I can make the thermostats work correctly. This problem really make me uncomfortable, I have to bear very hot or cold, turning on and off all the time. If this topic is not covered by your site, please tell me somewhere else that can give me the answer.

Thank you for your time.