From Business Insider:
The NBN’s chief executive has admitted the organisation has an image problem. Bill Morrow told the AFR that all the complaints regarding retailers not delivering on promised speeds does the NBN reputational harm, and says it would review the wholesale pricing model that the woes are blamed on. One solution proposed is to force retailers guarantee a minimum level of service.
I don't think it's just the retailers not delivering on promised speeds that is the problem here.
First step would be to build a network that's actually worth connecting to.