I confirmed the order with the car rental customer service before picking up the car, and received an email from the rental company saying the reserved car was ready. However, the counter told me the car I reserved wasn't available and recommended another model, claiming the diesel car was very cheap. The cost turned out to be more than twice the original order. My colleague signed the contract without looking carefully, thinking the doubled amount was a pre-authorization charge. What’s annoying is that the counter didn’t mention anything about upgrading the car. For such upgrades, informing the customer is the least they should do.