Greenmotion Refused to Refund My Reservation for Two Months After Failing to Deliver

I rented a car through Greenmotion, but they wouldn't give it back to me because I didn't follow their rental rules. They also didn't give me a refund for my registration fee. I still haven't gotten my money back after two months. I've tried to get in touch with customer service more than once, but I keep getting ignored or messed around without getting anywhere. It seems like they are avoiding their duty on purpose, which is unacceptable to me. They should be honest with their customers and give refunds if they can't do what they say they will do. Please take steps right away to fix this and return my money.