If OP (or his friend) was caught using a CDP he wasn't supposed to, it seems pretty drastic to put them on the do not rent list. The punishment seems harsh for what I'm assuming is a first time offense that may have very well been a misunderstanding. Why didn't hertz just try to bill him/her the full price of the rental without the CDP first? I'm new to the car rental game but this seems like the punishment doesn't fit the crime, unless this is just standard for car rental agencies.