Oxford Health care did not pay provider

I mailed claim form. The claims were not processed. I was told that they did not receive the forms. I faxed the forms twice because the provider was not paid. After many calls I was told that they "found" them, they were put aside and not processed. At this time some dates were over 90 days. Therefore the provider was not paid. I received a letter stating that I was called, I did not answer the call and they had come to a decision. I did not receive a call, nor did they a leave message. I called customer service 1-800-444-6222 and was told that the provider would not be paid. I asked if they reviewed the notes of the calls I had made and they did not write notes on all my attempts. I was told that I had to write an appeal letter. They only reviewed the dates. Oxford did not process my claim forms and they refused to say that they were at fault. I had customer service read back to me the note of this call. I hope the provider is paid.