Medical aid *****

I am not suprised that Bonitas has such a low rating. My son needed to go for a knee operation and we did all the neccessary formalities to get the procedure codes and Bonitas provided me with a authorisation number. And I thought having the auth number is my protection that the operation will be paid. After the procedure I was advised that 30% of my bill is not going to be paid because apparently moving my sons own ligament from his leg to his knee falls under prostetics. I am not covered for prostetics and therefore the paying short. How is this classified as prostetics in the first place. And why was this not told to me when phoning for the auth code. Please can some attorney help me? Or If I can get in contact with the Ombudsman? I am a single mother of Three and cant afford this This is absolute nonsence.