La Charme Rent-a-Car review: Europecar seychelles

I have a current booking with a Europcar agent in Seychelles — the agent agency who rented me the Europcar contract is La Charme Rent-A-Car. When I picked up the car on March 13 at Seychelles Airport, I asked the agent if I could extend the contract by 4 hours — that is, returning it 1:30PM March 17 instead of 9:30AM. She said there is an automatic free grace period of 2 hours but that I could only extend it by 4 hours if the car was available for extension. Today she informed me that another client has reserved the car, so I cannot extend it 4 hours. So I said “ok, I will just use the two-hour grace period and will return it 11:30AM.” She said, no, I can have no grace period at all. No car rental company on earth has no grace period capacity. Flat tires, traffic - all kind of things happen. Europcar has granted La Charme Rent-a-Car official agency status. And I want to register a complaint against them over this total inflexibility. I am a frequent traveller and have never encountered such inflexibility. I am informing Europcar that I will need the grace period on this rental.