This has happened to me in the past, but I have not done anything about it. Yesterday, from the airport, a VinaTaxi driver, first of all tried to charge me 30,000 vnd for the airport exit fee. The real fee is 10,000. Then I noticed he had not turned his meter on, and asked him what was going on. He replied it was 500,000 vnd to take me home to Nha Be. Whoa! Seriously! I'm outta here. I jumped out of the cab and had to go back to the taxi queue at TSN to get a proper taxi.
This has happened to me in the past with VinaTaxi, but never with VinaSun, or Mai Linh. Just a heads up for anybody new here, and if it happens to you, send a complaint, as I did, because the Vietnamese levels of government really do not want to have this kind of charlatanism carrying on. A lot of media attention has been given to try to stop this kind of nonsense.