Gems refusing to pay after registering PMB.

After a DVT I was started on Waferin and had to undergo regular INR tests at Pathcare. Despite the INR process being registered as a PMB condition, GEMS is not paying the Pathcare accounts!! Reason: incorrect ICD codes. I have made numerous calls to GEMS and also to Pathcare. Each one is blaming the other and I am stuck, as no corrections are being made, after seven months, with stale accounts to pay myself to avoid legal action. My medical aid, to which I must belong being a government employee, is really not rendering a proper service as they are refusing to supply me or my GP, at her telephonic request, with the correct codes to be utilised.