I’m still receiving bills for monthly payments even after my contract has finished, and I’ve left the country, SIM card has been replaced by a different carrier in the US. They say the service has not been cancelled, even with no contract, billing amount keeps increasing, BUT, they won’t discontinue service until the bill is paid. Has this happened to anyone else?
Optus contracts roll into a month to month contract at the end automatically.
You need to have either specifically told them to shut the service down or have ported the mobile number out to another company. have you done either of these?
There is no issue stopping the service with an outstanding bill. You can tell Optus at any time to shut the service down and that will stop any further billing. Even if in contract you can do this and you will just have to pay an early exit fee usually. Either way you will be issued a final bill though which will include any unpaid amounts to date. You can continue to discus with Optus what part of that bill you disagree with (for example they can easily see if you haven't used Optus at all in the months following the contract ending (0 data and 0 calls) and should normally not try charge you for that (although they probably are entitled)
I suggest you try Optus Facebook to get the issue sorted fast, but also perhaps write a letter expressly informing Optus of the closed account (when you closed it). Letters get more legal weight than other forms of communication