How do I file a complaint?

I have been on the phone with member services and the pre-authorization department for a total of 12 hours over the past week. There were so many things wrong with the service I recieved I hardly know where to start. I am no longer looking for a solution to my problem, instead I am looking for a person or department that can respond to and act on customer complaints. I do not want to call the Texas Department of insurance just yet, I want to reach somebody inside the company.

Does anybody have a suggestions?

Thanks.