Contact Nice Products at
https://niceproducts.com.au/contact-us/ They supply various locking nuts and the associated keys (see
https://niceproducts.com.au/nice-catalogue-18v3.pdf around page 286) and if you have the brand and code likely will be able to help you and give you the details of the nearest Nice Products retailer. You can also use the Irwin bolt grips etc to remove them; these:
https://www.irwin.com.au/tools/impac...rip-extractors or the similar Supercheap Toolpro ones i.e.
https://www.supercheapauto.com.au/p/...ce/342010.html