Currently trying to book a BA/QF fare HKG - Australia - UK/Europe - HKG in C

BA/QF has what they call a triangular fare which does just that, but running into a few glitches with the travel agent the company uses here...we are being told that we will have to pay for add-on sectors in both Australia and Europe based on the itinerary below? Does anyone have experience in this particular fare?

Fare rules state 2 stopovers allowed in Australia and 2 in UK/Europe...(doesn't mention anything about sectors)

HKG qf BNE qf SYD ba LHR / LGW ba MRS ba LGW / LHR ba HKG

Doing minimum transit in London both ways, only stopover in UK/Europe is Marseille. In the Australian portion, main stopover in SYD, but routing through BNE for a quick stop "home" (although only have time for <24hrs in BNE, so technically this is a transit?)

Agent here says they have to add on for LGW-MRS return and BNE-SYD....is this correct??? All help greatly appreciated!!

Thanks in advance.