Just to echo MostlyHarmless, I think you handled it extremely well.

I too would have called the police. I used to be guilty of letting my German Shepherd run off lead, but he was obedience trained and all I had to do was call him and he would come running. He was also never out of my sight when off lead. In my opinion, this lady was irresponsible in letting them out of her sight. Dogs as big and powerful as a Rott. can hurt you badly. Very well trained ones would not have come after you like that (at least I wouldn't think so).

LW