SC Rental Car

I am a frequent traveller to Italy. Last week went to Sicily and rented a car from SC rental car at Catania airport via the Discovercar platform. The car was in poor condition with many scratches but overall I have decided to take it. The lady at the checkout showed me the car, updated the damage list and that was all. When returned to the car, at the check-in in the man found that the door key could not get fully inside the door lock and said this was new damage. I mentioned to him that I never try to lock the car manually as there is a remote and this damage was already marked on the checkout list, he replied something like "Si" or "Yes" (has poor English anyway) and went back to his office. Then came out and said..Ok, your deposit will be back in 10 days.

Later I had an Email with the damage invoice. And today my credit card is charged a much bigger amount with no paperwork at all. No invoice, no explanation! Total rip-off. At the airport, they shared an office with ECH and Optimo Rent, so presumably, they are one and the same company but using a different brand. Will not use all three brands ever again and strongly recommend to fellow travellers not to do it!