No you aren't over reacting at all, we have had the same problem at my DD's school. A couple of weeks ago she ended up wetting herself because she was too scared to ask to go to the toilet, i was furious with the school!! They didn't even notice that she was sat in wet clothes all afternoon!!!!! It was the first time she had wet herself, ever!!!
It was really awful & my poor DD was so upset & thought i'd shout at her, but far from it, i felt so sorry for her!! I've spoken to the school, but i can't imagine it will make much difference!!