I read an article – a case narrated in it made me feel happy for guy who experienced it, make me feel proud of the folks who work in Starbucks:
One guy (on the way home) was late to buy a coffee for take-out. The cashier told they were closed already and cash register was off. She could not run transaction and accept money.That was a formal rule. She went beyond the formality.
She took the glass and filled it with coffee.
Here it is (You should not pay) Enjoy your coffee. And come again.
Put your customers before your products. Let customers live in a story which will be kept in memories & spread around !