Does anyone know of a store(online or otherwise) that would have a doll wig or extension/wig hair that is the color of the really old PM Felicitys?

Mine looks okay, but her hair is still REALLY thin in the back. If I shake her head I can see the wig cap and the spaces between the rows of hair. The front looks really good, and even her spitcurls are fine, it's just the back.

And lastly, are all of the Felicitys fairly thin in the back when thier hair is let down? The other PM Felicitys I've seen close up were always in a ponytail. I'm worried if I send her to the doll hospital, I'll end up with a newer head, non red wig, and possibly the same problem.