We arrived at HERTZ earlier than the scheduled pickup time, and they didn't have the reserved model available. The staff said we could only choose either a fully electric car or a manual transmission vehicle, or pay double the order price to upgrade to another option. I refused and suggested waiting to see what could be done. After waiting for nearly two hours, a senior employee helped us by offering a smaller SUV model compared to what we had booked. I had reserved a compact SUV capable of fitting three 24-inch suitcases in the trunk, but we were given a subcompact SUV where only two 24-inch suitcases barely fit. After storing the luggage, there was hardly any space left—even a large bottle of mineral water couldn't fit. I've rented cars abroad five or six times before, and this was the only instance where the rental company downgraded the car model. The service at the HERTZ Heathrow Airport branch is genuinely poor. However, the vehicle itself was in good condition—very new with only a few thousand miles driven.