Very high hidden ensurance fee & terrible customer service

I rented a car through EconomyCarRental, I needed to pay during the booking already a smaller amount and I got the invoice what shell I pay if I'm in Bari at the FireFly desk, where I physically rented the car. I paid all the insurance through EconomyCarRental, the highest amount what was available in the system. They are a kind of broker company...
Surprisingly, at the desk in Bari, FireFly did not take care, that I paid insurance via my online booking at all! They were saying, that even EUR 1500!!! needs to be reserved from my credit card as a cover for any damage or I paying ~ EUR 149 as an additional insurance! EUR 1500 is an unrealistic number, I never heard that such a high amount can be reserved as a cover, but not even my friends who use to rent cars frequently.
The only what Firefly was saying, it was a bad decision to pay online to the broker any insurance:).
After I came back from my holiday, I made my complain towards EconomyCarRental, via their online system. During 40 days I asked them 3 times, what's up with my questions, but I only got an automatically e-mail, that they got my e-mail, but no relevant answer at all. 3 weeks afterwards I opened my ticket again, I called their online service to follow my complain, they did apology and again nothing happened. Again, 10 days later I called them, already 40 days left while I initiated my ticket so I asked the supervisor on the phone. What she was saying to me I guess this is truly unacceptable in the customer services business. The outcome was, that I cannot read correctly the conditions. I was told that according to their judgment it is normal, that they don't respond during 40 days, the answer should be clear: we are working on it! The answer on the question why I needed to pay twice insurance, the answer: I did not read carefully the rules, and it would have been an option that they reserve EUR 1500 from my credit card:DD Ahhhha, because everybody has extra EUR 1500 on his / her bank account to not use it for ca 2 months till the bank make it again available...
For closing our "nice" conversation with the supervisor I tried to keep that in her mind, she or her company is living from me and from customers, and in this case, I'm the customer...
So, tell the truth fortunately I never experienced such an unacceptable customer handling at all!