Communication

I did use the AC more last year, because the owner remodeled and removed all of the screens. The first time I left the glass doors in the bedroom open, a bat came into the room. So I used the AC in the bedroom, only for a few hours each night. If that constitutes burning the owner with a huge electric bill, I guess I did. I am only trying to find out if 50 USD per night is a reasonable price. As it turns out, it’s probably outrageous.

Yes, US$50 a day extra for A/C is certainly outrageous. I think communicating with the property owner that you'll be careful with the A/C (maybe even offering an additional DEPOSIT that counts towards your final month) may resolve the situation as long as you make it clear that otherwise you'll stay elsewhere and they'll lose a renter.

I hate to see our visitors or our locals taken advantage of, and in this case it looks like it's you getting the short end. I hope you're able to resolve it amicably and satisfactorily.

¡Suerte y saludos!