At our cinema we have deals on concessions, 2 for £7 on regular and £8 for large. The deal is ONE drink and ONE food item, it's clearly shown with pictures.
Lady comes in yesterday, she's an Irish Traveller. (They turn up at our place all the time, they're rude, inconsiderate and always complain so they get something free).
She asks what the 2 for £7 is. I explain one food item and one drink.
She asks for two large Fantas, so I get them, along with one sweet and one salted popcorn.
Me: that'll be £16.
Her: why? It says £7.
Me: you asked for two of the deals, plus you upgraded to large.
Her: no, it says £7.
Me: yes, that's for one deal. One drink and one popcorn £7 is for regular.
She pays. Then a few hours later she comes back with half a bag of popcorn demanding a refund because "there was a hair in it."*