have been trying to change my life insurance policy with discovery for 5 months they are making it impossible

discovery has made it impossible for me to change my policy I am already a policyholder and they have all my medical details but they still sent a nurse to do a full test which she told me I passed but they insisted I had other medical issues which weren't even me it was my son and that I had to go to a doctor for further tests which I did but they still are messing me around saying they that they haven't received the results even though I confirmed with the doctor that they did send them then they askes more questions about the doctors tests I am just getting so frustrated with this terrible treatment