Refusing check in 40min prior to departure leaving kids stranded on airport

Refusing my son and 2 other kids traveling together as a group to check inn on flight claiming flight was changed by someone without wanting to give details who changed the flight made the 3 kids pay R500 each to change flights to next day - so the story makes no sense how can someone change 3 kids traveling as a groups flights and then they are refused to check in and made to pay R500 to change the flight leaving them without transport and accommodation - Pathetic service