Ridiculous service

My dad called nelspruit airlink branch to buy a ticket to fly back sunday, the ticket was booked to fly 11:30. the lady said he can pay when he arrives at the airport (OR Tambo) at least an hour before boarding. He was there before 9 am and went to the ticket counter to pay for his ticket. the person at the counter asked for the reference number which he gave to him, and the ticketman said his ticket had been cancelled as it hasnt been paid on time. and that it was off his system. my dad called airlink in nelspruit that he always deals with and they said they cant understand why the guy said that. he then had to buy a ticket for a flight at 3:30 and pay R420 more as the ticket counter guy wasnt prepared to help at all.. This is utter nonsense as my father had to sit and wait the entire day at the airport , when he should have been back home relaxing. and R420 more to pay is ridiculous as it was already booked