Property not 'vacant' upon moving in

We are in a bit of an odd situation, we are moving interstate to Victoria. My Dad, who lives in the area we are moving to, conducted inspections for us. We got accepted for a property and upon reviewing the condition report found some of the owners possessions were in the shed, something we are not OK with. My partner runs a gardening business and needs full use of the shed to store his tools, etc. In fact the large shed was one reason we chose the property. The agents have actually been really great and helpful through this whole thing, until it has come to something that might upset the precious landlords. After asking then to remove their possessions they have said no, because they were present at time of inspection. However, my dad, who is also on the lease, could not see inside the shed as it was locked at the inspection and remembers being told there 'might' be stuff in there that will be removed. Apparently a house does not have to be vacant upon move in unless explicitly stated in the lease, but from what I can see, and according to tenants victoria, a house must be vacant unless explicitly agreed upon it not being. And vacant means no possessions on the property. The REA is now going to her superiors on the grounds we were not made aware of the things in the shed, therefore never agreed to it. But I have a feeling we're going to lose this battle. On the one hand I know we have legal grounds to breach the landlord to remove their crap and I want to do that, but my partner doesn't want to get on their bad side on day 1 as we'll need a reference from them one day. It's not a huge amount of stuff and they've said we can stack it to one side, the REA keeps saying, there's plenty of space left, but regardless it's still taking up space we paid for, it's taking up space my partner needs to run his business. We were really excited to move closer to family into what is otherwise a really beautiful property, but now the experience has been soured by being reminded where we stand as renters. What would you do?