Danj,
Clearly ADSl2+ is not available in Williams Landing.
The exchange (Laverton) can support ADSl2+ BUT there is a RIM between the exchange and your house. A RIM is a sub-exchange needed for telephone and dsl connections in a distance greater than 4 km from the exchange.
The current RIM prevents anyone from getting ADSl2+ because the hardware doesn't allow it unless Telstra upgrades it which is unlikely because of the National broadband Networking stage 1 now (high optical fibers tech: no longer dsl tech).
Ask any ISP. Ask Telstra especially because they own all exchanges. If Telstra can't do it, all others can't do it too because they have to contact Telstra to connect the lines of the customers.
Hope you know this by now.