Bonitas failed to settle my medical bill.

My hospital bill that is less R1400 is partially paid by Bonitas and some parts of it is declined. During my recent inquiry about the matter, I was told that it is because of a late request which to me doesn't make sense because everything on the invoice was suppose to be declined if that was the case. I have called the authorization department several times but none of the people I spoke to seem to have a clue of what was the reason for the decline. Initially when I called I was informed that the partial decline was due to the pleura space ultrasound (ICD10 : M79.99) was not within the Practice's scheme rate and now I am told that its due to late request. I contribute a lot monthly to be medical scheme to be treated this unfairly. ***