I just got back from a trip to the UK to see my mother. One day before I left a convenience store clerk short changed me one pound. I got him to give me the correct change. I was born in the UK, now live in Canada and of course sound like an American(Boston accent ?). So it seems to me I get taken there on a regular basis both because of my appearance and accent. LOL the next day as I am buying my train ticket with two mins. to go before departure I hand the train clerk a 50 pound note(bill to you!) for a 37 pound trainfare. He gives me 3 pounds change. I said what about the 10 pounds? He hands it over. Lesson learned - dont be late for a train as you dont have enough time to report the cheating clerk to his boss. Being reasonably assertive should be instilled in you as a kid asap.
You dont have to be an a.........e to be assertive. Just stand your ground. How is it the older I get, the more amazed I become at people