Missed our flight due to slow passport control

We were booked with an Airlink flight (SAA 8154) to Ndola on 26 December 2014 from OR Tambo. We handed in our baggage at approximately 08h15 and had coffee with family members. The flight was scheduled to depart at 09h45. We had to stand in a very long queue to have our passports stamped. Some of the check points were closed and the few staff members struggled to handle all the passengers. We arrived at the departure gate shortly after it was closed at 09h25. There was nobody at the departure gate, and when two staff members arrived there, I was informed that the flight already departed. I first thought that this was a joke. We had to collect our baggage and return home. during this period we heard from several other passengers that they also missed their flights. This is totally unacceptable as this was due to the negligence ACSA by not employing more staff as this was a public holiday and during the Christmas season. Another shock awaited us when we heard that our return flight from Ndola was also no longer valid as we didn't show up. Flight Centre is prepared to refund the airport taxes and that s it. What was suppose to be a joyful experience ended in a nightmare.