Yeah, you also ask for a break on the rent for putting up with no heat when it's turning to winter. The landlord (or slumlord) should provide you with space heaters.
Nobody's going to find 42 degrees acceptable. I'd take pics of the thermostat and document everything. That's freaking nuts.
Or if they can't provide heat, the landlord should set you up with a hotel room. See what your lease says.