Holy cow. What happened?
https://www.aarp.org/health/medicare-insurance/info-2020/obs...
I hope you all the best. We live in a Second World country.
But I also suggest physically going to your congressperson’s office (the local one in your district, not DC) and explaining the situation. Instead of calling/waiting for a response.
Good luck.
A man who is going to die because of an incompetent government clerical error is the kind of thing that makes for a great outrage story.
And will also likely get someone intervening at a high level immediately once it's the subject of the news.
You shouldn't have to do this, but as far as methods within your grasp to fix it - it can be one of the most effective.