Discovery does not pay for cancer

Seems discovery does not cover cancer. I am registered for oncology for my skin cancer condition. Before I went to have 3 cancerous growths cut out, I phoned the oncology department at Discovery and got the icd 10 codes etc and was told all was good. Had the procedure, the lab results came back cancerous, the Dr charged the correct icd 10 codes yet Discovery says that my savings are depleted and will not pay for the procedure. This has been going on since June with motivational letters from the Dr etc, still same outcome. Yet you have the lab results saying its cancer, I am registered for this condition under oncology and the icd 10 codes are correct. Eventually I paid the Dr out of my pocket. My next question is, this is the type of skin cancer that can spread to the brain and lungs, if that happens will that costly treatment be expected to come out of my savings as well? Very disappointed, been a Client of yours for over a decade and this is the service and cover I get....