No Client Service!!!

I received a bill from a medical supplier who said that Discovery did not pay my account, because apparently I did not have authorisation numbers. I had an authorisation number for each and every visit to a specialist. I have sent the bill to them to try and clear it up. After that I sent 3 more e-mails. No answer. I was even on the phone with them and after holding the line for 20 minutes and being transferred from one person to another, they dropped the line. They may be one of the biggest medial aids with many benefits, but they are definitely not the best. On the contrary, I am really sick and tired of trying to get client service out of Discovery!!! And the only way to get service from them is to complain publicly.