Sorry if this has been covered in other topics but just wanted to share our recent experience with rentalcars.com
We rented a car from Newcastle to drive around the lake district. After much scrutineering using several sites we went with rentalcars.com because they ostensibly did not charge a young drivers fee and included all local taxes.
We handed over via card what we thought was the total amount for the car rental only to discover when we picked up the car that we would need to hand over an additional £90. We originally thought the whole rental would cost approximately £60 so this was quite a shock.
We've contacted rentalcars.com twice on their website but with no reply.
I would strongly recommend not going with this website if you're booking a car. Their app claimed that what we were paying the whole rental price online but in reality we ended up paying more than double what we anticipated and our complaints fell on deff ears.
As we are tourists it seems that there are few options for holding rentalcars.com accountable.