I'm kind of disturbed that the director didnt know about the first incident. Any kind of "incident" in my daycare requires a form signed by a parent, teacher, and the director on the record.
After the first time it seems like they tried to fix it with the table leg, after the second time IMO they should have provided some kind of chair with a strap. DD's daycare has small chairs and I think they all have straps. Like Amber said, I assumed those were required!