Car rental damage scam

When we returned our car yesterday to Sixt the agent got down on her hands and knees and looked underneath the car and stated we had under body damage and no insurance covers under body. She called the manager and he had her put the car on a lift. They decided we had damage and charged us 45,000ISK (331 US dollars). We didn’t see what they were saying was damaged and we only drove on main roads, no F roads. When we got to the airport I received an email with our return receipt. The receipt stated no new damage and under remarks stated no issues. I’m feeling scammed. We will never rent from Sixt again.

UPDATE-After replying to an email survey I received from Sixt and detailing how I felt they committed fraud I received an email from the manager and they are going to refund my money! I will still hate them forever and never use them again.