Return policy unacceptable

I have been ********** by this airline. Tried to book online for qn adult and two kids, the price it showed me did not indicate it was just for one person. Because i found it a very reasonable price, i went a head and booked it. Only to find out after making the payment that i was charged three time. Immediately i contacted them to correct this. They blatantly refused to reverse my transaction. I find that absolutely not fair at all. I am told of terms and conditions. Clearly this is pure *******. Why are people customers not allowed make mistakes? It's not fair. What makes flight tickets exclusive to any other purchase?