Pegasus Airlines Cabin Baggage Allowance Dispute

I changed my flight with Pegasus from Ercan to Ankara to a day earlier because they canceled the flight and rescheduled it for very early in the morning, which I couldn't make. Even though I had cabin baggage allowance, the only option available for the change was the light flight. I called Pegasus and they said there would be no problem and that I could change my ticket, and they assured me that my baggage allowance would be assigned after 24 hours. When I checked after 24 hours, I saw that it wasn't assigned, so I called again. They said the cabin baggage allowance had been filled, and they would have to put my baggage in the hold. I told them I had medical equipment in my baggage, so I couldn't give it up. After that date, through at least 10 emails and phone calls, they finally said they had added the cabin baggage to my ticket as a note, but I would only be able to use it if I checked in at the counter three hours before the flight. When I asked what I would do if the Pegasus representative at the counter said, as usual, 'Sorry, our cabin baggage limit is full, we have to put your baggage in the hold,' they said I could report my grievance after the flight by calling. After giving up my medical device to be placed in the hold, if I call them afterwards saying it got damaged, they'll probably just say, 'You shouldn't have given it if you didn't want it to get damaged.' As a result, I want the cabin baggage allowance that I previously had to be reissued on my ticket for my flight scheduled for a week later.