I took two of my queen size down-filled pillows (8", firm density) to the cleaners. I asked if they could clean them, especially the shell. I pointed out that they were down filled, they said "Yes, no problem". I went to pick them up ($12/pillow) and they were flatter than a duvet. Consequently, I royally complained and they said they will send them back to where they are cleaned to see if they can do something to puff them back up again.
I wonder if your pillows were so old that the cleaning process destroyed the down. I have now experience with down, but I do know that feather pillows wear out over time. Perhaps down will last for decades, but I suspect that age was a factor. Have you had them cleaned in the past?
You could take them to small claims court, but it won't do any good. Even if you had a receipt saying the pillows were 200 dollars when you bought them, a judge would say that after 20 years their reasonable life expectancy was zero. In other words, you've gotten your use out of them.
Question: Did you sign anything? Was there any warranty? Any guarantee? Did you ask?
If there is a warranty or guarantee, you've got something. They must back up any guarantee they gave you.