Honesty
I decided to buy takeaway because I was too tired to cook Tuesday night so I rang my local kebab shop and ordered several things. Not that I'm greedy, but if I spend £7 or more it's free delivery.
Anyway, I totted everything up and it came to just £7.30. Food was delivered and he said £10.30!
I said
"how much?"
We went through the menu and the delivery man said he reckoned that the guy had totted things up wrongly. Anyway, to cut to the chase, the guy took £10.30 off me and said he'd check it when he got back and, if it was wrong, he'd bring me my change.
Half an hour later he brought me my £3 change back as I'd been charged double for something so I gave him a tip for the honesty and trouble he'd taken.
This is one customer they won't lose.