Pre approved claim not paid

Bonitas are not paying doctor for extracting wisdom teeth- I had pre approval. This is from January 2018, on statement of Jan 18 the doctor's claim was listed as unpaid, so I phoned to find out what's happening. Bonita's told me the was an error please resubmit. So I re-submitted , and nothing happened . I inquired again , and Bonita's denied receiving it . So I submitted again, and again nothing. When I inquired again, I was told it was to late and would not be paid , but if I can proof (screenshot) that I send email , they can look into it. I send the proof and claim a couple of times and received a email back stating that they had received it. Needless to say -nothing happened. What more should I have done????