Does insulation count as habitability in a rental?

We’ve had loads of problems in this home since we’ve moved into it. The landlord finally getting around to fixing make habitability issues after 6 months.

One of the issues was faulty electrical work. Part of the insulation had to be taken out above one of the rooms to access the wiring. Before the insulation was removed, I could heat the room with a small space heater. Now that it’s removed, I can’t get the room above 35 - 40 with the current weather we’re having. (The central heat does not go into that room so it has baseboard heaters. But to get the room to warm up at all I have to run the baseboard heater and spacer heater continuously which is making our electrical bill skyrocket)

Landlord essentially told me the bundle up and that they will not be replacing the insulation in that room. I’m worried about the increased heating bill and even getting the room to warm up in general due to there being no more insulation in the space above the room.