I am livid!!

I have my step daughter for half of every week. I bathe her nightly and brush her CURLY hair at least twice I day. but every time I pick her up shes in filthy clothes, smells is in a dirty diaper and hasn't had her hair brushed in days. I've talked to her mother (my ex (Long story)) about this multiple times and nothing has changed!!! tonight I was brushing her hair before her bath and this came out.

I am at my wits end on what to do! She's living in a place with access to a bath and a washer and dryer and I give her plenty of diapers and wipes every week. I don't know how to talk to her anymore, she's obviously not listening to anyone. (my mil has talked to her about this also and given her special shampoo and conditioner for her hair) and the worst part is my step daughter is only 2!!!!!! so she can't say anything about it. my step daughter is spoiled, whiney, and throws absolute freak out when anyone touches her or shes told no. I'm trying to raise her the best I can in my time givenp but I'm at a loss here. Help???