Lack of transparency gives me sleepless nights...

My trouble started in February 2017, after my wife and I became regular blood donors and I already donated a couple of times. When I heard the news in February 2017 that according to their records, they cannot accept my blood, because I did not declare that I was on medication. I never went to any doctors for the past 8 years, and the only medicine I use from time to time, is Grandpa Headache Powders. I amalso not a drinker and does not use narcotics. They told me Icould not donate blood until April 2018. In April 2018, I went to donate blood, and my blood was accepted. SANBS still couldn't tell me what medication they found in my system, or how it came into my blood. In April 2019, I donated blood again at Centurion Lifestyle Shopping Centre, and without any problem. This year April, I went again to Lifestyle Centre to donate blood, and this time my blood was rejected again and this time, for biological reasons. This freaked me out, and I immediately asked the nurse if I was tested positive for HIV. The nurse told me that there is no such information on their system, other than 'REJECTED FOR BIOLOGICAL REASONS'. I went to my doctor and asked for a blood test. My blood test results came back as normal. I just want SANBS to show me decency and tell me why my blood is rejected so regularly? I sent many emails recently to them, but my emails stays ignored. Please tell me what is wrong with my blood, and how I can remedy any defects.