Unpaid hospital vlaim

I Dudu mbatha *** would like lodge a complain against fnb I was admitted @umhlanga hospital on the 23rd of May and discharged on the 29th of May 3024 ,on the 6th of June 2024 I send the claim documents to fnb as I used to do when I'm claiming ,than after calling them now and ghrn to check status for the claim that supposed to take 10days as usual and a positive response ,what surprise me on the 11th of July received an dms that tells me that claim was declined and not happy with explanation , pls help I trust you