You have to request the bundle by phone and make it clear that you need the Uni-V connection. They are able to provision it, however the default for NBN and NBN Co's preference is the VoIP based NGC, which is why Telstra use that as the default.
Generally however, if you request it, and inform them that you currently have that on your current setup there shouldn't be an issue.... shouldn't...
In a store they should also be able to do the same, but online you wouldn't be able to do it.