See, what you gotta do is threaten them with absurdity.

Don’t say “I’m never coming back”. Instead, walk across the street to the bus stop. Wait for them to come out to their car. Memorize it.

Now come back to the parking lot every day for a week. Wait for them to leave their car, and go inside. Once they’re inside, you walk over to their car, and write down their liscense plate number.

Now go home, and use public records to do a search to find their name and address.

Now go back to the store, and take a picture of them with your cell phone.

Now, sit across the street from a police department, and watch for a cop arriving to work. Take note of his liscense plate, and search his name/address.

Now write a letter to the clerk, threatening to wait outside his work with a giraffe. Tell him “Giraffes have 15 inch tongues, thick as a beer can. I’ve trained this one to stick their tongues into your butthole, and grab your waist with their teeth. You’ll be 19 feet in the air, getting tongue fucked by a giraffe. If you try to escape, you fall. See ya at Costco, Gary!”

And you use the cops name/address as the return address. Now if he tries to go to the cops, they’ll protect their own, and find something to arrest him with.

Checkmate, Gary!