do you have a heat calculator (as in on the entry to the home) or do you have those plastic things attached to the heater?

If it's the latter, they do not measure any physical units and the price per unit can vary drastically from year to year. Had that problem back in Poland, but that is a bit longer story.

I would have to check the rules of the heating to say more. Can you show me what the counter looks like? some quotes from the heating costs calculations by your landlord would also be good.

Anyway, if that is the case, I'd advise to find a new apartment.