I have been through this a number of times with Jetstar but simply get back fob off emails. I once even got a free flight....which I refused to accept out of principle.
Jetstar often sells flights out of Melbourne considerably cheaper than the same flight out of Sydney. Sometimes it omits offers for Sydney customers altogether.
Today Jetstar offered 2 for 1 flights from Melbourne to Osaka, Japan for $479 (direct flight) whilst from Sydney to Osaka, Japan the cost was $543 (with a stop in Cairns). This is outrageous and clearly Sydney customers represent no value for this company. The fact that Sydney is Australia's most populous city has apparently escaped this company as it abuses and rips off Sydneysiders.
There are other airlines out there who do this route and whose prices are pretty good. Given the extra baggage charges it might be appropriate if Sydney people avoided being being done over by Jetstar and voted with their feet.
Not happy Jan!