Medical bill question

Get Aetna to send the Rush Medical Group a letter stating what you are and are not responsible for and have them CC you as well.
When Rush hits you up again, call Aetna again and tell them you're being contacted by Rush to pay a bill that Aetna has said you are not responsible for.
Aetna will then send them a letter telling Rush not to call you again and telling you not to talk to Rush again.
Kick back and let them fight it out.

At least, it worked for me with a hospital and United Health Care. When the hospital threatened my credit, I sent that to United too. Got an apology letter from the hospital. Mistake. Sorry. Oops.