Hopper complaint: Purchased Ticket to RSW with Oxygen

I purchased a ticket to go to RSW from PWM for Aug 2. I was positive that I added Oxygen to my reservation.. Apparently It didn’t show up. Day before I was to fly I was checking in and saw that it wasn’t listed on my reservation. I called them. I have never been denied boarding because of not having 2 batteries to my portable oxygen. First of all this isn’t drs orders. It is recommended as I have COPD. I have flown many many times and never had a problem until Aug 1. I was told that I had to fill out paperwork to be able to bring the oxygen on the plane. I did that. I called the oxygen dept at Delta. I was told I needed to have 2 batteries. I am from Florida. I had to make a few phone calls to local oxygen companies in the area and found out that no one carried the same oxygen machine that I use. I called them back and they said I could not fly if I didn’t have 2. I called delta and told them that I needed to cancel the flight and they said they could not cancel the flight because I went through you. I tried to do it on the app and I failed.. I was also packing up to drive an hour to catch a flight from Portsmouth to Punta Gorda that was leaving at 8:30 pm. I had to leave Monday night as I had a drs apt on Wed. Morning. I could not find a flight that I could afford with any other airlines for Tuesday. I tried to cancel and thought I had gotten somewhere as I got an email and it said I had 3 days to cancel . I relaxed a bit after I saw that. I was in a rush to get to that flight that i had to get on since Delta was refusing to let me fly if I did not have 2 batteries.