Things like this make my blood boil. I've worked in legal for years and have a lot of experience working with, for and against medical providers. When I have an issue I will put every complaint and concern in writing and then I fax and mail it to them. Forget the phone I like faxing things to them. That way you have a time stamped date of request. They don't like that.
If you can't get their fax send them a letter, certified if you're really mad. Outline all of your prior requests in your written correspondence and state what it is you want them to do.
You can also leave a review on Yelp or Google. That tends to get results. I really use these tactics as a last resort. They've really complicated things for you so it's time to play hardball! Good luck to you and your parents!