Sue -
Didn't I mention that the Movers sort of did that, too! They loaded our stuff, then got to the new place & started to unload, and then the head of the crew said to me "I'm sorry. I forgot. We ahve to collect from you before you can unload." But at least he was nice about it!
I had no problem though paying them because the amount was correct based on the hourly rate I was quoted. Just took more hours than anticipated (Elevator out, power failure, etc.)