Any chance a neighbor may be hooked into your setup? I did have a neighbor’s security lights on my bill years ago. A screw up on their end is always a possibility. I hope you can talk a a real person who can help you. A $500 bill would give me a heart attack.

My two cents. Get a Kill A Watt and check your appliances, etc. An old or dying fridge, etc can play havoc with your electric bill. How old is the hot water heater? A bad element can draw lots of juice. Do some investigating.

I also suggest leaving open cabinets that house any plumbing. There can be cold spots on exterior walls where the insulation isn’t up to par.

Kitty Treats! Please!

Open up any cabinets and/or closets so heat can circulate around your pipes. There can be cold spots in the exterior walls that can lead to pipes freezing.

No, they are harmless. I was concerned when they showed up in the fall last year. I rescued the first few I found toodling around my sink, but a lot of them came into my basement. They were attracted to the nightlight I had up for my cats. The worst thing they do is die.