Unpaid claim under pmb

I app**** for pmb because I needed to visit specialist after my funds were defeated. 1 session was tha approved I than see a specialist with cash since she was not taking medical. I phoned gems about claim procedure and I was told to forward invoice to enquiries. I did but no response after 5 day I forwarded invoice to complaint department, they responded within 4days to say the claim was declined due to incorrect ICD10 code. My frustration is before I submitted the invoices no one told me about Icd10 code. I was told that the only thing they need are the invoices than banking details. I need some help here pls