J.M.
As the mother of a former "bite-ee" I totally hear your frustration. My daughter was bitten at least 8 times, all by the same little girl. She even got bitten on the forehead when I was standing right there! It was awful. My daughter was in a larger center, and after the first couple of times, I was told that they were working with the biter, its normal, etc. After the 7th or 8th time, I told them that, while I appreciate that they have an obligation to try to meet the needs of every kid, and certainly a financial disincentive to boot kids, my child was being injured at their school and it was simply unacceptable that they couldn't keep her safe, whether or not it was "developmentally appropriate." Ultimately the biter had to have a one-on-one aide all day unless she was sleeping, and even still, her parents ended up pulling her out of the center (she was biting more kids than my daughter - sometimes 5 or 6 times per day!) Her parents were so upset; nothing was helping. The mom literally had to take time off from work and stay home with her because no center would take her and they couldn't afford one-on-one care.
I guess my long winded story is just to say that I suggest that you try to ride it out for now. If she's bitten again, talk to the provider about what specific steps you can take to keep the children apart, because it's highly unlikely that punishment is going to help. You can also ask the provider how many bites it will take for her to tell the biters parents that she can't care for that child anymore - everyone should know so that if the child does have to move elsewhere the parents are prepped for it. But I wouldn't threaten to pull your kid unless you're planning on staying home for now, because this is a problem you're going to run into absolutely everywhere.
Good luck. I know how much it stinks.