I am trying to use up my companion voucher I got from the RBC BA Visa and my next big trip is to Australia/NZ in Jan. I would like to fly business class and don't mind stopping. I was under the impression BA can fly YYZ-LHR-SIN-SYD on one itinerary but I just called executive club and they said I would need to use partners to get to SYD. My voucher only applies if I use BA metal. Does anyone know if there is a way to get from YYZ to SYD using only BA? I don't mind leaving out of ORD or JFK/LGA if that helps.

Thanks.