Anyone taken Harvey Norman to disputes tribunal?

I want to take Harvey Norman to disputes tribunal, who is the right person to put on the forms? The store manager, the GM of Harvey Norman NZ (which is owned by HN Australia)? or the Australian CEO of the shell company?

I bought a product from them which physically broke in under a year (part of the plastic broke causing the item to be unusable) They sent it back to the manufacturer who said it's physical damage and not covered under warranty. I think as it's not durable HN are responsible for resolving the issue. Any advice?