BEWARE OF THIS AGENCY. We rented a full-sized car in June at Heathrow, fully paid in advance, and my credit card was charged for the full amount upon booking (2 months prior to arrival). Our flight was delayed, so on arrival at the rental desk l I was told our reserved vehicle was no longer available, and I would have to pay an upgrade for the next available car. Complete BS, my car was FULLY PAID, they should have held it indefinitely, they had nothing to lose. Just a scam and a way to take advantage of travelers who are stuck in a foreign country. Holiday Autos hides behind the shield that they are "just a broker", and the actual rental company enforces the terms. In our case, we were a few hours later than originally indicated on our rental agreement, so they claimed the car was rented to someone else, and we had to pay for an upgrade.