Captain refuses taking children 30minutes before d

My children were scheduled to leave Saturday morning at 11:10 from OR Tambo to PE, we got to check in 10:45, Nishen the guy at the desk said we are late. I told him but we're here 30 minutes before departure, he then phoned the host on the plane to ask the captain if they'll take the kids. After a few seconds they sent a message to Nishen's phone of which he showed me stating \Hi Nishen