Steady eddy,
I have had the same experience with Qantas and Jetstar as well, whilst discking round confirming with family/partner, by phone or shouting down the hallway, on time date etc have timed out and/or the seat has gone, it's called the real IT world. There ARE others out there doing the same, "first in best dressed".
One exercise over a morning had three seats on the same flight all business colleagues who checked in with me to confirm times etc at different times then prices.
Was only $20 bucks or so but still waaay cheaper than it used to be.