That pretty much goes with all the taxi company's in Oslo... And they don't speak very good Norwegian either. Of course, some of the drivers are perfectly fine, I used to have a phone number for one of the drivers I knew I could trust, and who knew how to get places. They don't necessarily know much about the city, or the difference between Vinderen and Lindern, or Skoyen and Toyen (opposite parts of town). I used taxis and chauffeurs alot in Norway, and it is usually no problems. But as said, if you want to make sure you get a good guide, the taxi companies is probably not the best choice. Unless they have a certified guide as a driver.