Had the same thing happen with Telstra last year. I’ve never even held an account with them and started getting a paper bill for a mystery 60 bucks. Went round and round with them for nearly 12 months accruing hundreds of dollars in “interest” before they wiped the debt. Fucked that the burden of proof ends up on you to prove you never started the account. Apparently the scammers sign up online for a 2 year phone plan with your ID, get the phone delivered somewhere friendly, never pay the bill and then sell the phone.