OMG
, You were way nicer than I would have been!
I can not believe that as a groomer you have been using for soo many years and they injur him soooo severly and say nothing. Did they have someone new working there? Did you call them back and tell them that it was NOT just a little cut that a huge chunk was missing out of his ear?
I dont know what the process would be, but I would say first you would have to take him to the vet to have it assesed as to have proof how the injury occured.
I will keep your baby in my thoughts and prayers. Keep us posted to how things turn out.