Budget car rental charging people valet to boost their income amd robbing people off

I returned a car i hired. On return the person assisting me wanted to force me to sign a declaration that the car was excessively dirty so that they can charge for valet services. The seats were spotlessly clean, slight dust and a little sandy because of rain then they claim they have to send it for valet. For all i know they will charge me and use their vacuum cleaner to clean the dust off. Budget rental has now found a new way of robbing people. No where on the contract where it says if the car is not clean you will ne charged for valet. If it was excessively dirty thats understandable.