Pathetic customer service

<p>Yesterday, I flew to East London on a business trip and my company booked a Corolla or similar car with Avis. when I got to the counter, I was told that I have been upgraded free of charge to a Mercedes-Benz C-class which I accepted. This vehicle was in such poor condition with scratches all over and it was extremely dirty inside. After returning this vehicle, I got a call today from an Avis agent informing me that a small key which is found on the inside of most Merc keys is missing and that I am liable for this. I informed him that I do not know anything about this as the key was handed over to me without that small key inside it. Despite explaining this, the agent still sends me a form to accept liability for this small key that went missing. </p>