Discount ruined my car rental experience

My experience with discount was awful. I booked and paid for the car for a one week rental to be ready at 2:30 p.m. I arrived at 4:30 p.m. to pick up the car and was told that there was a problem. The vehicle they were supposed to rent me had not yet been returned by the previous client and they weren't able to reach him on his phone. After humming and hawing they asked me if I would be able to go to a different location to pick up the vehicle. As i had a trip planned and wanted to get on the road sooner rather than later I told them I would do whatever needed to be done to get a car. With that they attempted to make arrangements with other branches but without any luck. I had hoped I could pay a premium to park my personal vehicle at their location for the duration of the rental but was told that was impossible because they have a 75 vehicle fleet and so they dont have space. That itself made me laugh given with such a large fleet they didnt have a car for me for a booking I had already paid for. I took advantage of their offer to follow me back to my house to park my car and shuttle me back to their branch. They assured me by the time I got back I would be all set. When I got back they had a HYUNDAI ELANTRA ready. I paid for a full size car !!!! When I told them it wasnt the class of vehicle I ordered he went back on his computer in what I thought was an attempt to resolve the situation. Instead he looked at me and said "your reservation was 230pm....its 430pm ...its not our fault we dont have a car...if you were here at 230pm there would have been no problem" I PREPAID FOR A RENTAL FOR A WEEK. as far as I'm concerned that car should be there and ready for me to pickup at anytime during the rental period that I so choose. Their proposed solution was for me to sit and wait for a vehicle to be returned. At this point I was getting rather frustrated and as the branch closing time quickly approached I feared I was going to end up leaving there