We had a cab driving scam us in France. We were docked in Marseille and wanted to go to Aix. We were 6 people and one of us spoke fluent french. He did the negotiations with the cab driver. The deal was to be $50 Euro each car round trip. Two cars were needed. They would drive us there and return 4 hours later to take us back. Well, we get to Aix and they want us to pay them $50 Euro each now. We said we would pay half now, half when they return and thats when the cab driver suddenly tells us it was $50 each way per car. Well, that didn't fly with us and he kept trying to say we didn't understand. So, we call over the Police and sure enough they were trying to scam us. The drivers had however run the meters while they brought us there, so the Police said we had to pay the meter (which was about $50 E) however they wrote up each driver for about $150 E each in tickets. The female officer was wonderful. Very kind and helpful, and took care of us well. We ended up taking the bus back which turned out to be very cheap and just as easy if not easier.

So in this case, we understood perfectly but you are held hostage with a cab driver sometimes. We laugh about it today though.