Update 31/08/20:
Infinet sent the headphones back unrepaired, and Sony is refusing to repair since there is "corrosion damage". They also sent a photo of the alleged corrosion:
I told them I don't agree with the assessment. Also, I pointed out to them their exclusion policy, which is for liquid spillage or abnormally corrosive conditions. Still no go.
So I've reached out to ACCC to explore my rights as a consumer. Wish me luck!
Original post:
I'm legit pissed now so I apologise if I'm not coherent.
I bought my WH-1000XM3 in October last year and it worked well until it started to have the infamous rustling noise issue in my right ear cup. I can share a couple of links pointing to this. Apparently the new XM4's have a similar issue in the right ear cup.
So I sent it per Sony's instructions to their service solutions provider (can I name them here?), and was told to contact them. I was informed it was a corrosion issue and hence they will not fix it. Which is in itself strange because I've never used it for exercise (why would I use such an expensive headphone for that), but it is as it is.
And then I was told I'd be contacted for an invoice to get it back. When I asked what for, the person said labour is not free, you know? I'm absolutely flabberghasted. I got on the phone with Sony Australia and it's being escalated but what are my options?
Your options are to get on the phone with Sony Australia and make a forum post on Australia's foremost bargain sharing community while you await their response.