This one sticks in my head because of the level of absolute rage displayed.
This is about 40 years ago - I was a teen working at the Customer Service desk at Sainsbury's. It's Saturday, it is busy, and there is a queue. An older, tiny, neat and well-dressed lady arrives at the front of a queue, huffing her displeasure at being made to wait. She has a toaster. She explains it is not working, and she wants to have a refund.
It is in a Tesco own-brand box. She confirmed she bought it from Tesco.
On being told it wasn't something we could help her with (with a polite explanation) lady who looked like someone's beloved sweet grandma exploded in a level of foul-mouthed aggression that caused the 6ft Viking dude in the queue behind her to step back in shock (and cover his child in the trolly seats ears)
She was screaming so loud that 'one fucking shop is the same as the next fucking shop and just give her her fucking money' that onlookers came from all over the store to goggle while she grabbed display stuff and threw it at the staff counter, emptied the whole of the sandwiches and wraps on the floor while screaming truly shocking obscenities.
Luckily, the crowd she drew in to gawk intervened when, in a final volley, she threw the toaster at my head and launched herself at the counter to climb over and attempt to slap me in the face.
Four of the men in the queue grabbed her, lifted her off her feet and manhandled her out of the shop.
I am sure it would have been recorded and posted on the internet these days, but it was before mobile phones (and in the years when smaller stores didn't really have security)
In those days, they didn't take it further, and they certainly didn't really back up the staff, so I was told to go deal with her and apologise a few days later when she came back to complain about how she was treated and to 'get her toaster back'