Incorrect date

Be warned, be extra careful when booking flights - I inadvertently booked a return flight for my son and grandsons on the 26th April from the Gold Coast when it should have been booked for the 27th, the same flight my daughters and other grandchildren are on. We are all travelling up to the Gold Coast on the same flight.
It was a simple key stroke error and on checking our itineraries yesterday i realised the mistake I have made. I rang Jetstar only to be told they could only deal with my son, even though I made the bookings. He rang them to be told it would cost him $600 to change the flight by one day. You can imagine what he told them to do. So, I rang them and my son gave them permission to discuss it with them. I explained the situation that it was an error in entering the details and I was prepared to pay the $74 fee to change the flight. Well, they then went on to say there was a booking fee of $200 per passenger, this was despite the fact that the flights were on special and were being advertised one hundred dollars cheaper than I originally paid. I just couldn't believe what they were telling me.
Out the goodness of his heart, the man I was speaking to said he could bring the charge down to $365. I still thought this absolutely outrageous and asked to speak to his superior. When she came on the line she was quite indignant that I thought this was unfair. She went on and on that she was giving web price, even though the fares were so much cheaper, I just couldn't work out what she was talking about. She eventually brought the fee down to $265 which I begrudgingly agreed to. She put me back on to the other person I had dealt with only to be told she had removed our extra baggage which i had already paid for. I was absolutely distraught and couldn't believe it.
That would have meant I had to repay the baggage fee. I told him to forget it and leave everything as it was.