I had one try to raise the price by about 10% after they had my items. It was an interstate move and the company I had contracted with and that was named for loading, transport, and unloading on the bill of lading sold the job to another mover. I guess this is pretty common, but it's also pretty illegal. Without a valid bill of lading they are in possession of stolen property. I told them so and asked if they wanted to involve the police and the DoT. They unloaded my things then.

It's one of the rare occasions I've stiffed someone on the tip. If attempted theft and extortion isn't a reason to reduce a tip, nothing is.