Hello XXXXXXXXX, I understand your disappointment.
To the absolute best of my knowledge nail polish remover can actually eat a hole in some materials(I saw this happen once) and you are right ,it doesn't work.
Some say acetone based remover will work by blotting but I've yet to see proof.
You might want try the dry cleaners for a product that might help.It can't hurt to give them a call.
Honestly the last time my wife spilled polish on a long white cotton gown she ended up embroidering over the spots in an attractive way to be able to still use the favorite gown. You might try something like that if appropriate.
Thankyou for your question.
father of many,grandfather
God made children so we'd learn how to love