I actually had problems with my Marisol's hair and have simply styled it in a style I like and left it.

originally, I requested a replacement from AG, which they sent, but then couldn't ever convince myself to ship her off, because she's my first AG doll and on top of that very special to me.

I ended up paying for the replacement and keeping both, so I now have an extra Marisol to sell/trade later on.

I think it all depends on if you seriously think it is a wig defect, or if you think it might be dog related. Also if there appears to be obvious damage caused by the dog, ex. bite marks.

I don't think I'd ask for her head back, though. Never really under stood that concept, but I don't see why asking them to fix something that appears to be an actual problem if you feel it's honestly not dog related.