if she worked for me, I would deffo sack her for talking to a customer like that, never mind a 2 year old customer!
But if it were my shop, I would want to know of the complaint before reading it in the local paper.
I have officially changed my mind, I think you should complain to the shop first, and if you don't get any joy there, then complain to anyone and everyone who will listen, local paper, radio, whatever...