On my main selling account I've just had an INR case opened and the item is showing as still in transit.

It was posted on Thurs 7th Dec & then a week later the customer lodged an investigation with Aus Post without bothering to contact me. I also opened an investigation which resulted in the item finally showing it had moved to the buyers state. Sadly the items tracking has stalled again - hence the buyer opening the INR. I have to respond to the ebay case by 27th Dec.

As Aus post won't resume deliveries until the 28th, what's the best course of action as I haven't responded yet?