Going too far

I had a customer come into the office yesterday. He was a very elderly man w/ a cane and had 2 girls with him (turns out they were probably his grandkids). What he was asking for was something that took the manager a few minutes to find. We only have 2 chairs in the little reception area and the girls had already sat down when I told him it would probably be a little while. So he told one of the girls to move and let him sit down. Understandable. The girl got up but was all pouty and complaining that her sister got to sit. That man took his cane and struck her right on the side of her leg!!! I could not believe it. I was just so shocked. The poor girl tried not to cry but of course did. And he basically told her in the gruffest way possible to change her attitude. Like I told my co-workers, I agree she needed to straighten up and I don't have a problem with spanking but right there in an office and with a CANE!!! And he didn't get her backside but the side/back of her leg!