Adler Alvin L MD

I have seen Dr. Adler for a few years. Yeah sometimes a wait but he is good and knows what he is doing. After my last visit I will not be returning. He did some acne procedure, but was nothing out of the ordinary, and I was never told this was going to be extra. Then a month later I get a nasty call from his office telling me I owe $ 100+ for a procedure I was never told would be an extra cost. I understand coverage with insurance changes but its bad business not to tell patients a service is going to be extra and hit them with an extra charge.
I canceled my next appointment after this as not sure what extra charge they will bill insurance and not tell me until after the fact and hold me responsible for.