Originally Posted by
Globaliser
I suspect that this is the problem. SYD-LHR is in one particular Avios zone. A booking for SYD-SIN + SIN-LHR, or SYD-SIN + BKK-LHR, will be calculated using different Avios zones. And the rules say that you can't change an Avios ticket into a different redemption zone - you have to cancel and start again.
oh dear , i was hoping just to pay the extra avios involved
might be worth ringing up again and speaking to someone else everyday lol