Dress alteration question

So I have a weird question I’m hoping someone on here will have the answers too. I was given a dress, unaltered size 12, that I can alter and wear for the wedding. I’m not in love with the dress but free is budget friendly. Problem is, I’m no where near a size 12. My street size is 2-4. Is it possible and would it even be cost efficient to alter the dress down? If it’s going to be $600+ to alter it I’d rather go and get something I love. I called one alteration shop who said they won’t take it in more then 2 sizes but if someone has experience and say it can be done I can call others...

thank you!