does it happen during the same day?

my D. was bitten twice by the same "offender" (the daycare director's word) during one day. I was very upset too. This is what you can do:

Make it clear firmly to the director and the teacher that you are very concerned about the situation. It is important for them to realize that you are not happy about it. Tell them safety is the very first thing you want for your child.

Ask the teacher/director when and how it happened. Discuss with them what can be done to minimize the chances that it happens again. In our case, it happened in the morning during a fighting for a toy, in the afternoon on the buggy ride. So the teacher decided to put the "offender" closest to her on the back seat of the buggy, this way she can have time to react if the child to about to bite. They also promised me to separate my child from the offender -- however for how long, I am not sure. Perhaps a couple of days when the memory is still fresh.

At last, I am sorry to say that biting can't really be eliminated at this age... Good luck!