Zipcar Abusive Charges Newton Massachusetts

So I reserved a Civic using the app. The price was around 9.50 paper hour. I received an email about the reservation, with no price on  it - like I am used to receive all the time.

Every time I reserved a zipcar since May/14 I would get a discount per day, so let's say a car at 9.50 would cost at the end of the day around 80 - 90 dollars. First reservation was from 2pm to 5 pm on a sunday.

So I was with the car and had no data working on my phone and needed to extend the reservation. So I sent an message to extend the reservation. All well, like before.. And then again, I needed the car for more time. And so I did, until 10am the next day.

Later on the same day I decided to make it a 24h reservation and to my surprise it would claim that my card couldn't be charged.. I thought it was weird because I already had reserved more than enough to get the whole 24h with no extra cost and also knew my credit card limit. When I finally got data access, I was chocked: a total of 155 dollars charged!

This is an absurd, I've always rented zipcar and never ever had problems like this.

I wrote them an e-mail and they replied me saying they wouldn't refund for I rented a car that is charged by the hour, not by the day. When I booked the car there was absolutely nothing different on the e-mail or confirmation, nor on the website, not even on the text message. I am sure about this. If zipcar has cars that are rented per hour  they must be properly communicated to the customer and not induce the customer to error like I was.