I Was Charged Extra By Centauro Despite Insurance

I rented a car from Centauro in Alicante through their own website and paid for premium insurance ahead of time to protect myself. As soon as I got to the counter, the staff started pushing me to buy an extra "local" insurance policy that would cost me almost €250 on top of what I had already paid. They said that my current coverage wouldn't work and that I would be responsible for any scratches, dents, or damage, even if another driver in a crowded parking lot caused it. I said no because I knew I had already bought full protection. But they still charged €1000 directly to my card, not as a deposit but as a real payment. They also charged me €95 for gas and said they would give it back if I brought the car back with a full tank. The whole thing seemed dishonest, and I don't trust Centauro anymore.