Giving our seats away is not okay

My girlfriend and I went to Cape Town for the weekend and booked our flight back to Lanseria Monday morning (15th of Feb) 6:10am take off. We got there at 5:20 and stood in the Q for the self service check-in, but when we got to the machine it stated our flight was closed and the security guard pointed us to counter 93. We got to the counter at 5:35am where the lady behind the counter informed us that our seats had been given away because check-in closes 40min prior to take off. There was no announcement that the flight was going to close, nothing. There was still 35min left and our seats where gone.. We had to pay R1623 each to get on the next flight to Lanseria. We then got an sms from Mango apologising for our delayed original flight, which only took off at 8am! But.. Because she already gave away our seats, we still had to pay for the next flight out. It's absolutely ridiculous that no one announced the flight closure and gave us a change to check-in at the counter! I've never heard of 5min costing someone R3246, its absurd!!<br> Guys and girls, be aware of this and know that they don't care about their clients. Its all just about the money.