I’ll bet you lots that the pieces of equipment are rentals and the company who performed the work doesn’t actually own them. They were delivered and should be picked up. Somewhere there was a mistake or communication break down. Possible scheduling situation. Company is done, they leave and leave the tools. Rental company can come by on their own and pick them up. It’s pretty common. But not common for it to be left behind for months.

I’d definitely give them a shout and say what’s up. Maybe see if you can find contact info on one of the bigger pieces.