Escalate to Management

I have been struggling with Pathcare for the last 5 months, since my mothers death. One of the tests were rejected by her Medical Aid. The Medical Aid indicated that it is an extra charge that has already been funded on this claim and that no one is liable for the payment. Pathcare does not care. Even after getting the necessary information from the Medical Aid and requesting Pathcare to resubmit the claim on the correct code, they refuse. Pathcare are also not willing to talk to the Medical Aid directly to sort out the issue. What does Pathcare expect? That I just pay the account, no questions asked, even though I know the claim was incorrectly submitted to the Medical Aid. What about Pathcare try and help and contact the Medical Aid? I tried. Now I am expected to just pay?