Claiming GST and duties back on a new bike returned to Wiggle

[JEF Perth]

Hi folks, I would really appreciate any ideas as to solutions on this one as currently I feel like I'm living in a cycling nightmare version of Groundhog Day.

The scenario:
Purchased a bike from Wiggle. As it entered Oz I got a call from DHL asking to pay GST and other duties (c$350) in order for them to be able to deliver it to me. That happened the next day. Unfortunately parts on the bike were not as advertised which I raised with Wiggle who offered a full refund (on what I paid them, not the taxes/duty). DHL arrived the next day and 2 days later Wiggles money arrived back on my credit card........

The problem - how to claim some or all of the GST/Duties back?:
Wiggle said it was DHL's issue as I paid the GST to them > DHL said it was a Customs issue > Customs said it was an ATO issue > The ATO said it was a DHL issue > Who said it was a Customs issue.......etc, etc

So far I have done 3 full circles, escalating each time, and I am still none the wiser not any closer to getting any money back!

I can't imagine that I am the only person in Australia who has ever returned a bike to Wiggle (or another overseas retailer) and then tried to get some of the tax back.

[queequeg]

This might be a good place to start:
https://www.border.gov.au/Busi/Duty/Refu

[Stuntman]

If you paid the duties on a credit card, and cannot get joy from DHL, etc raise a dispute with your CC provider.