I'm just appalled by that teacher's attitude. Her defensive comment about it having been three weeks tells me all I need to know about her. I don't care if it takes three months, that lady should be willing to work with your child! Preschool is when children learn to love school, to adapt to the transitions between activities,and to get along with the other children. You didn't mention it, but does your son get along with the other kids okay?
My daughter's preschool handles "problem" kids by having them sit in the director's office quietly for a while. Or another teacher takes them aside for a different activity. They know they're not getting to do what the other kids are doing, but there's no public humiliation with sad faces or "bad" color charts. I volunteer at my daughter's preschool all the time and two of the kids didn't get to help me with a fun project yesterday because they acted up and made other kids cry during recess. They just went inside with the director while the rest of us worked outside. There was no big deal about it, no production, just a quiet separation of the two who were misbehaving from the rest of the kids. The other kids didn't even notice, they were so excited about our project.
Anyway, if there is no other teacher available, you need to tell the director you'll be looking for another preschool next year. Yes, your child will have to learn to deal with difficult people and difficult personalities all of his life, but starting that at age 4 is asking a bit much. My daughter will have to deal with mean girls and teenage bitchiness down the road, but that doesn't mean I would subject her to it every day while she's not even in kindergarten yet! Those challenges can be dealt with later on when she has a bit more maturity and a bit more self confidence.
Good luck to you!