Careful about insurance options

I had gotten third party insurance for the car and explained to easirent that I already had insurance and didn't need it. They still made me put down a sizable deposit which they said would be fully refunded, but then somehow charged me 27 pounds a day because they said I had asked for a reduced deposit. I had questioned the +1,000 pound deposit which they said they would reduce to 150, but then charged me for it. It is in the fine print on the contract after looking back over, but they quick talked me into it at the counter as they rushed me through the sign in process. So just be careful!