Listen, I was in retail for a long time. Misgendering people is a very easy thing to do; you don't know how an individual you don't know wants to be "pro-nouned" in whatever their situation is. I usually approached groups of people as folks, as in; "hi folks, what can I help you find today", instead of "Hi ladies", just to not be offensive or create an unwanted awkwardness.
As for this particular situation, yes, go straight to corporate, explain the situation, and demand at the least that HR conducts sensitivity training per the law. I certainly, if avoidable, would not frequent the establishment for a while, they don't deserve your hard earned money.