Plane overbooked

Due to come home to Durban after a 2 day business trip I'm informed that the flight is overbooked and will only be able to get a flight two hours later. What concerns me I was able to track down 12+ people who were supposed to be on the original flight. Not to mention that my pregnant wife had to wait 4 hours for me to arrive. I would like to know if this is standard practice, to mislead the customer by charging a premium for a false promise to get you on time at your destination, because there are no issues when they accept your money.