I wonder how much attention you would have gotten if you'd headed for the door with slow and sure purpose with the items and without paying! Bet they'd have time for you then!

Stop at the front door (if they don't chase after you), drop the items on the floor, and declare, "I WAS just gonna leave with these, since you don't want my money, but I decided I don't want your SH**." Then go out the door.