Dishonest and underhand behavior from Budget/Avis

I have, on many occasions, used rentalcars.com with great success. In November 2018 I happened to get a vehicle from Budget/Avis. All went well, normal great service until dropping off the car at OR Tambo. The vehicle was checked, thumbs up given, we went on our way. Received a call while in departure lounge from Avis (they are the same now?) asking if I was aware of damage to the front bumper. I was not, there was no incident or damage and the guy JUST checked the car. Nothing was said, nothing was signed, nothing was disputed. There was no damage. They have, of course, deducted money off my credit card. Unacceptable. I will not be using this web site or this provider again. Dishonest and *********. What is the point of having anyone check when you deliver the vehicle if this can be done?