This is a subject where you need to be naming names. If a given venue is making it hard for you to enjoy a show after you have purchased a ticket that establishes your need for special seating, they may be in violation of ADA law and at minimum are just being uncaring and awful people. I have witnessed sports and entertainment venues bending over backwards to accomodate disabled people, as they should. If a venue isn't doing that, let's hear who they are, and make sure you email them a copy of your post. That's how you change things.