My mother has New Horizons by United Health care and we found out that if Medicare didn’t pay for something then neither did New Horizons. She had to get rehab therapy (after something too long a story to tell) and we ended up with a 10k bill. We appealed and of course the administrative judge found for the insurance company.
Can’t you buy ‘medicare supplemental insurance’ to cover stuff like this. I plead ignorance on this subject, due to my age.