Enterprise Rent A Car - Temecula ripped off deposit and refund Temecula California

We rented a vehicle from Enterprise in Temecula for a week (Saturday to Saturday) at $284 including tax and paid a $100 deposit, for a total of $384.  On Monday, the day after a heavy rain, my husband was driving in a rural area on a dirt road when the road gave way and he slid.  He was able to get the vehicle out and after cleaning it, it seemed okay but did have some scratches on the bottom.  On Tuesday, when he was parked, he noticed it was leaking what looked like transmission fluid, so he turned the vehicle in at the nearest Enterprise (Ontario Airport).  So he only had the vehicle for three days. 

We filed a claim under our own insurance, and Enterprise charged us another $500 for the deductible.  We were expecting to get the $100 deposit back and to get credit for the four unused days we had left on the rental, as we didn't get a replacement vehicle.  But that didn't happen.  Enterprise said that because we didn't have the vehicle for the whole week, which was at a discounted rate, we would be charged the daily rate for the days we had the vehicle, and somehow they maneuvered things so that we didn't get any refund at all.  They said that we were now being charged $308 for the time we had the vehicle.  But they also had said that the daily rate for the vehicle was $50, so I'm not sure how that comes out to $308 for just a few days, even with tax, etc., added.  We were paying with tax, etc., about $40 a day with the weekly rental, so the weekly discount wasn't all that much.   

Also, they are saying my husband turned in the vehicle Wednesday morning, but it was actually Tuesday morning, the day after the mudslide incident.  So even then we are being cheated out of a day.  I don't know why they are saying Wednesday, unless it was turned in what had to be just minutes after their "deadline" so that it's considered the next day.  Which is BS.  

Anyhow, I feel that we should have had about a $260 refund.  I don't know if it's worth trying to take them to small claims court or if their sticking it to the customer is legal maneuvering on their part.  Legal or not, it's not ethical, and I will NEVER AGAIN use Enterprise, and I will do my best to convince all my friends and family of the same.