You will currently have to stop over at least once to get from South Africa to Cambodia. You can fly directly into either Phnom Penh or Siem Reap – both of which have very modern, efficient airports.
The quickest and easiest way to get there is via Singapore – 10,5 hours to Singapore and then an hour and fifty minutes from Singapore to Phnom Penh on their regional airline, Silk Air.
The cheapest way is usually through Hong Kong on either South African Airways or Cathay Pacific and then a regional airline directly to Phnom Penh or Siem Reap. There are also flights through Doha on Qatar Airways and Emirates via Dubai.
Cambodia is five hours ahead of South Africa and seven hours ahead of Greenwich Mean Time (GMT).