Beware my lazer eye beams!

Today I stared daggers into the soul of an incompetent cashier at Lowe's. She was literally shaking, which made me feel sort of bad but no less angry.
I had a very simple return. A bag of items I'd decided not to use. Nothing was damaged, no packages or labels of any kind were missing or tampered with. I had a receipt. It should have been a ten minute transaction at the most.
Here's the thing, I don't have a hot temper. Last time I lost my temper with another grown person was seven years ago(roommates argh). I can pretty easily process anger and tune it to the appropriate level for the cause.
I also have had enough experience on the other side of the cash register to make me more than understanding when there's a glitch in the system.
Today the glitch was the cashier. It was obvious to me why the transaction wasn't going through the way she wanted it too, but she couldn't see it.
I am itching to type out all of the details but that would benefit no one, you'd be bored, I'd be angry again and that poor woman would probably feel the wounds I inflicted on her soul with my eye daggers begin to fester.
She said to me "this (the receipt) is the Bible, and the computer is never wrong, so I don't know what the problem could be" I knew what the problem was.
In the end she was unable to give me a full refund. She patched together two thirds of my money in a series of ill conceived transactions and finally gave me the bundle of receipts and the remaining items and told me to take it back to a different location and try again.
I knew I'd never get a full refund if I left the store at that point but I had no choice. Baby Girl's dance class would be over in five minutes and it is a 20 minute drive to get there. I ran through a list in my head of friends who I could call and ask to pick her up but I don't know the dance teacher's address, just how to get there. It's a messy drive, lots of turns with even more available wrong turns and I don't even know the names of any of the streets. So, I had to leave.
I'm not taking her advice to go to a different location though. I'm going back to the same store where I will tell the manager all the particulars of our exchange in a last feeble attempt to get my refund. I hope it's not enough to get the poor woman fired, I would feel badly about that. Still, the whole affair was ridiculous and needs to be set right so to the manager I will go.