@Az-Lux0
I think there might be more to this story than what you have mentioned. I am not sure if it was the same listing, but this guest stayed in January and a guest who stayed in December mentioned "however when we entered there was a dingy box fan on in the basement which was apparently placed there to dry up water from some kind of leak. This made it extremely cold when we arrived on an already record cold night." So, it sounds like you knew about the heating problem and leak well before the more recent guest's arrival.
Both these guests mention a number of issues, not just the heating in the basement, and those issues are repeated by many of your other guests and seem to have been going on for a while. Cleanliness in particular seems to be a problem, including trash, but also pests, lack of amenities, and problems with the AC or heating. In each case, you respond angrily to the guest and accuse them of making it all up, but I only scrolled through your most recent reviews, not all of them and these issues came up over and over again. The ratings for both listings are low, so it seems like this is not the only guest to give you a low score.
I don't know if this guest is lying or not, but if I was you, I would listen to the feedback from your guests and make improvements to your cleaning and deal with the other problems too. You claim in one of your responses that you have a 5* cleaning crew, but it doesn't sound like they are doing a great job at all.