Howler *****ing customer moneys by selling one ticket twice

I bought 3 tickets on howler for the Luju Festival in Eswatini ,2 adults and 1 child.when I got to the venue I was then informed that the child's ticket had already been scanned. How?? Basically someone was able to ***** my child's ticket. This is concerning as we share our card details on this site so if it is unsafe then Howler is putting us at risk of our money being ****** as well. If the ticket was not ****** then how was it scanned before I even got to the venue? Why didn't the ***** ***** all three tickets? Or is howler running a **** where they sell the same child's ticket more than once hoping the other child won't attend? What is going on? Is Standard Eswatini aware of this **** as Luju Festival is their product?