I offer free English lessons to people who mostly work locally in low-paid jobs in the hospitality or retail industry. My students are of all ages and from all sorts of backgrounds - and are usually very appreciative and hard-working.
I got an enquiry a few days ago from the owner of a local restaurant who was phoning on behalf of his wife and we made an appointment for him to bring her along today to meet me and fill out the forms. Fifteen minutes after they were due to arrive I called to ask where they were. They hadn't forgotten, he simply said it wasn't convenient for him today - I told him that although the lessons are free my time is not cheap and that I object to him wasting it, at which point he became embarrassed and finally said a reluctant 'sorry'.
I think he was just plain rude and I am still feeling cross even after doing a great amount of cleaning!! (It's what I do when I'm bothered.)
What bad manners make you seethe?