I had a similar problem. When I got my two girls, they had been beat up durring breeding attempts. They were also undersocialized terribly, and my violet wrap, Dharma, was badly fur bitten. That is why the breeder was selling them, they were to stressed to attempt to breed again and she was 'reducing her herd'. Really, I think she had gotten over her head and didn't have enough time to spend with all of the chins that she had, and was good enough to recognize that the animals weren't getting th attention they deserved individually.
When we got Lily and Dharma, they were very stressed out and didn't want anything to do with us. If we even went near the cage they would freak out. It took us 2 months alone to get them ok with us being in the room and to get them to come out of the cage at all. After months of coaxing, treats, and patience they will now come out of the cage on their own, sit in our laps, crawl on our shoulders, and greet us when we come in the room. Dharma grooms my boyfriend's ears (its funny to watch), and Lily likes to play massage therapist. It just took alot of time.