200% penalty admin as per Europcar with zero proof

I hired a vehicle from Europcar in March last year. In September I was notified of a fine. I requested a copy of the fine however clicked on the link sent to me to pay the same day, which payment included an admin penalty. 2 days later I get an additional invoice with a value of over 200% the value of the fine as an additional admin penalty from Europcar themselves. I queried this along with the copy of the fine and Uriel said she would request the fine. Dumisile basically said they could charge whatever they want as the contract states "an amount" will be charged. Despite that I am waiting for feedback and have sent about 15 follow ups in this regard - they have now handed me over to hybrid debt collectors. Still no response!