Pathetic Kulula

Yesterday afternoon I checked in online, the main reason for checking in was so that I could preselect my seat. My girlfriend and I have been booked on separate references so to ensure that we get seated together I checked us in and selected our seats. A while back I had called the airline to ask if the can pair the booking as so that should the be an aircraft change we will remain paired together. I was told this was not possible. This afternoon when I get to the drop off, no surprise we where given separate seats and told there was an aircraft change. This defeats the purpose of checking in online and for the life of me I cannot understand as to why the airline cannot pair a booking, simply pathetic. It pains me that we had bought return flights and I have no faith that on our return when we check in the same will not happen. Safe to say on our we are greatly disappointed and chances of flying kulula again are slim to none.