I’m definitely not condoning their actions, and quite possibly this not calling back may be a good thing as it may be a representation of their business practices.
I know of 2 electrical contractors in western MN and one in eastern SD who have shut their office line voicemail off, and have instructed their employees to not add any work to the books, as they are booked up with work for nearly 12-14 months. Some of these guys are so busy they aren’t even taking on subcontract work for low voltage system installs on the same commercial projects they are doing the power & lighting on. Working all day saturdays and half day sundays. That gets old in a hurry. I’ve got tens of thousands of dollars worth of side job work I could take on in MN just for buddies that farm and need electrical work done around their farm sites.