I'm working close to HR, your case is entirely HR fault to not mess up the location so they have responsibilty to cover your moving cost. They can make it up by two ways
1) pay you relocation cost at reasonable price
2) pay you living away from home allowance which maybe both benefit to you and your company as it is tax free from FBT, PAYG and payroll tax, and you don't need pay any tax either
Don't worry your fight will effect your potention future in the company, as a big legal entity, they are not so fool to challenge the law. Good luck!
