AVM is only for 80% LVRs. I think you've done the right thing, get your broker to try the AVM and if it's not working for a loan increase at 80% then use the full vals.
Yep I outsmarted it for a client last time. Full valuations for other lenders came back at $300,000, did a CBA loan increase @ $350k and it was done. Silly in my view.