I booked a car through booking.com at Bergamo airport (Italy). The car provider, Locauto, was appalling. They didn't have the car I booked and they were terribly rude. We thus proceeded to rent a vehicle elsewhere. Upon my return I contacted booking.com for a full refund which I received promptly with a letter of apology for my bad experience with Locauto and a discount voucher for my next booking. I can't fault their costumer service and courtesy both on the phone and by e-mail.