Over charged for children's airfare

They charged my children as adults and when I'm informing them l, they giving me the run around that it wasn't indicated initially. If you over charge someone and they brought it to your attention, you rectify that and give them their refund and charge them appropriately. Have they forgotten the Consumer act? The customer protection act? Or they just want to ***** innocent people money? Their service is really going to the dogs. Guess the lawyers are going to get involved in this.