Complaint

It's the mark of an advocate's respect and dignity that he/she be dressed in the proper outfit as the etiquette deems. And if, in fact, they fail to do so, they'd be subject to court's contempt and be punished with fine/imprisonment. However, such punishment depends upon the court's discretion and the fact that such incident took place in the court. I doubt it would be possible for you to file a complaint in this regard.