Thanks for all the advice and updates on here, has been so helpful but still no luck getting refunded for my cancelled return flights to London (NZ2/NZ2). Today they offered an alternative flight with a different carrier..wasn't expecting that.
I've tried the US DOT rules but they are adamant that I am only 'transiting' and that DOT sees it that way too. They agreed that if I had booked NZ6/NZ2 I would be eligible for refund. I will file a complaint with US DOT anyway.
I also tried the EU 261/2004 REGS but they said because I am NZ resident I am not covered by this but if my flight originated in the UK I would be covered. I argued that my flight does depart from the UK (the return leg) so the ruling applies. Their response was that since its a return originating from Auckland this doesn't apply. Now I have looked into it I can't see this anywhere in the ruling. I read in the EU ruling that also the outbound and return flights are always considered as two separate flights even if they were booked as part of one reservation. Therefore would have thought the return flight meets the air passenger rights as it ''departs from the EU to a non-EU country operated by an EU or a non-EU airline''.
Wondering if anyone has had any luck with getting a refund using the EU REGS?