No Shortage Of Gas Here

My carbonated water machine has run out of gas so I bring the cylinder in to exchange it for a full one. I see a set of boxes of the cylinders I need, but in front of them is a sign that says, “If you are exchanging cylinders, do not take one of these boxes. Please go to the checkout to exchange.” So, I do. I tell the woman at my register that I am exchanging my cylinder and she starts processing the exchange as I’m extracting my old one from my bag. Then, the cashier at the next register speaks to me.

Cashier #2: “If you are exchanging, you just come up here; you don’t get one of those boxes.” 

My cashier and I both look at her, confused.

Me: “That is literally what I am doing right now.”

Cashier #2: “Those boxes aren’t for exchanging.”

Cashier #1: “She didn’t bring a box.”

Cashier #2: “You just come up to the registers with your old cylinder. We have to give you the new ones from ones we have behind the counter.”

Me: “Again, that is exactly what I am doing. I do not have a box. I read the sign.”

Cashiers #1 & #2: “There’s a sign?”

Me: “Yes.”

I tell them what it says.

Me: “And that is why I came straight up to the registers and did not bring a box.”

My cashier is finishing up my transaction.

Cashier #2: “You don’t take the boxes—”

My cashier interrupts her to start chewing her out a bit.

Cashier #1: “Why are you telling her to do something she already did?” 

They were still discussing it as I left. Not sure what was so confusing about me doing what I was supposed to, not having the thing I wasn’t supposed to, and already being helped by someone else who wasn’t having any trouble.