Store sold dirty display model and refusing return

Hi everyone,

If I am wrong and this is how the law works then fair enough. I disagree with the ethics, but whatever.

I bought an item for full price for 400+ AUD. They are snow goggles. The store gave me a display model. When I got home it was dirty and apparently scratched according to the store. I tried to return it but was told they always clean their display items and ensure it is sellable before giving it to a customer. Clearly not in my case. They blame me for the damage.

I sent a dispute to my bank and they denied it. This is my first time ever disputing and I am not some scammer. I spent 2k+ in that store and the 400AUD item is the only one I am disputing.

Proofs I gave my bank:

1. Receipt showing I paid full price... expecting a new item.

2. Images of item with full labels including flimsy "asian fit" paper label. If i used it that thing would melt off in an hour. Proof that it couldn't be heavily used.

3. Email from store admitting it was a display copy but they always clean it. Blaming me. Ignoring to address I was sold a display used model at full price without being told.

4. Email from store showing proof i tried in store and via email to resolve the issue with the store.

My bank declined it saying the store did everything right.

Is this true? If it is true then I lose faith in our system because this feels so wrong.

If not then will Fair Trade help me? Do I call my bank again? It sounds like they closed it as final.

Thank you