Doctors Note

I was supposed to take an SAA flight from JHB to CPT on the 28th March 2016. But i fell sick and i couldn't make the flight. I went to the doctor and received a doctors note. But when i spoke to the call centre agent, she says that they only take hospital admission notes. A medical doctor declared me sick and unable to travel yet SAA will not refund my ticket. I demand a full refund please. Booking reference Z8YQWS.