Boarding Finalized

Plane ticket for my wife booked through Computicket - flight from Jhb to Dbn at 06h50, Tuesday 1st Sep. In line at 06h10 with just hand luggage to check-in, only to be told that the flight has been finalized, and she can NOT check-in and board. She along with the many others were advised to make amendments(to me looks like a new ticket) which costed another R928 to book the very next flight which was scheduled to leave at 08h55 (amazingly the next flight had available seats).<br> <br> One has to check-in minimum 40 mins prior to flight, i can't see how she could not have checked-in with one bag(hand luggage). Would that minute have delayed Mango's flight plan??? Often when passengers are on time and the flight is delayed then its OK, T&C's don't apply!<br> <br> Is this how customers are treated?