Claim Not paid

I submitted a claim and was partially paid. When I called to query they told me the code used was wrong. The doctor will not change it because she says its right. Now I'm torn between the two. I asked the consultant to call the doctor to explain but they don't want to. The service is appalling and I don't understand why I have to go through this when I pay my monthly contributions. I have spoken to 4 call centre agents already who were no help. when I request a manager or senior personnel they refuse. I am fed up.