...almost double the deposit? I think I was scammed today.

I went to rent a car at an Enterprise Rent A Car. Firstly, over the phone earlier during the week I was told told I wouldn't have to pay any insurance and that the deposit would be $250 for the car. BUT when I arrivd at the East Coast location not only did they double my deposit to $250, but they MADE me pay various insurance fees. I asked them, SEVERAL times if it was necessary, and they insisted that it was.
a) Why do I pay a larger deposit ($500) when using a DEBIT Card Visa versus a CREDIT CARD Visa.
b) How do I report this Insurance overcharging scam and what else can I do to protect myself from Enterprise?
c) They also CLAIMED they had no car seats (for my baby) but made fun of me by stating that they could lend me a GPS system at an additional FEE.
I felt totally violated today, life on the East Coast often SUCKS.

I just wish I could live my life without dealing with such overcharges, discriminatory treatment and arrogance.