Contact pioneer Australia and ask if they can supply you with spare parts. You can substitute pioneer with any HU manufacturer which have bluetooth HUs. Unless, and this is a long shot, you have a friend with a 3d printer who could fabricate one for you.
In my CU2, I removed the factory mic from its location near the sunroof switch, and tucked this pioneer mic in the space. Stealth and factory looking.
In my previous car, I tied a cable tie around the mic, and instead of cutting the excess tail off the cable tie, I used it to tuck it into the top of the A pillar. Again, less cumbersome, and much neater.
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