I have a third party multi city booking with QF flights between MEL and NRT. While I can open the seat map on the QF website and app and 'select' seats, unfortunately my choices can never save because I reach my last QF sector and it always says "5 of 7 flights". I booked 6 sectors, and then with the phantom 7th sector qantas can never let me go past it and save my selection. Any ideas are much appreciated!