You need to talk to the right person and you need to visit them. They never have returned one of my calls either, so you're not alone.The other thing is I don't consider a crack in paint work 2 inches long a very small defect. It won't be long before moisture gets in and under the paint and I will be stuck with the cost of the repair.
I guess like most dealers, they don't usually jump through hoops to fix issues unless it's a government recall.
Arrange to meet the dealership manager, take the bike, take the photos and work with them on your solution. Which is, replace the fuel tank thanks very much. If not and there is absolutely no other reason for the crack other than faulty workmanship then the law is on your side from my understanding.
The brand is a fledgling in the AU market so Victory Australia doesn't need bad publicity and to dissuade customers from their products.