Hey there. I am blind so I understand your frustration. However, I think you will have much more success in general if you give companies/organizations the benefit of the doubt instead of being so confrontational from the start. I find it’s typically not that they deliberately decided to exclude blind/visually impaired users but rather that they just didn’t consider it at all.
As you noted, we represent a tiny share of the market, so it’s quite probable they have never had any previous contact from a visually impaired user of their software. Maybe give them the benefit of the doubt and assume yours is the first such complaint they have received.
Did they ever get back to you on this?