Rented a Mini from Sixt for 12 days in December 2022. Added an additional driver to the booking at the counter for a whopping charge of 149.99 which I accepted. However, on final bill they also added an extra 30 pounds "premium location fee" TO THE ADDITIONAL DRIVER. To be clear, I had already paid a premium location fee at time of booking. This was an extra fee added because I added another driver. I can see no way why I should pay again for the premium location (Heathrow) because I add another driver. The additional driver ended up costing an extra 25% of the whole booking. This was crazy and was not made clear at the rental desk. I complained to customer services twice with no resolution. I wouldn't use them again, as this was unfair and clearly profiteering.