While I agree that a comfortable nights sleep is key for a hotel, the problem with central AC systems exists in lots of places in Europe and also Japan. They really should have a way to at least turn off heating if too warm, but as I understand it often requires a trained technician to come in make the changes and likely someone will complain one way or another.

I had the same issue just a few weeks ago in an exclusive Onsen (hot spring) resort in Japan where central heat was pushing room temperature to 27-28 degrees and opening a window wasn't possible as they had no insect screens on windows and bugs were storming the room in minutes. Btw, that place cost 500€ a night. No remedy other than getting a fan for the room for sleeping. At HI Milan Garibaldi I had the opposite on a very chill night in May where room temperature was around 16 degrees and AC had been switched to summer cooling already.

Getting back 45k points is pretty good already, though the hotel or IHG shouldn't make it his hard to get recourse. These issues will remain unless rooms all get individual ACs which is probably a long way out and just not common in some parts of the world. A pain. YMMV.