Overbooked flight!!!!

I am using the extra hour I have been made to wait at the airport to write this complaint. Not only was my original flight overbooked, I have been stuck in row 72 practically in the toilets on the next flight. How is it even legal to overbooked flights? SAA is suppose to bensure South Africa's premier airline, yet this is my first time flying SAA and definitely my last. How is it acceptable to charge people premium Sunday afternoon flight rates and then completely mess up their travel plans? Not even an apology or any consideration at all. Simply blaming the horrific service and inconvenience on a call centre error. For the money one pays you would at least expect to have get a seat on the flight you book. SAA's slogan says there is a story in every seat. My seat is one if disappointment, anger, inconvenience and disgust. And considering the seat on my new ticket, severe discomfort too.