The actress left the project over "artistic differences", she told The Sunday Telegraph.
Madonna is now looking to replace Stilley for the role of Lady Thelma Furness in the period drama.
"I had the role, but we had artistic differences. She (Madonna) is really something. I wish the cast luck because they are all really talented," Stilley said.
Abbie Cornish and James D'Arcy are starring in the picture, which is scheduled for a 2011 release.