I have direct payment set up for my account *moderated*. However the credit card (AMX card) has been cancelled which I try to edit and provide a new credit card for payment. I tried before the payment is due and today as weii without any luck on line with my account. Please let me know how to edit and change credit card for my direct payment.
You can manually pay your bill anytime. A direct debit will only take out any left over debt, so if you have paid it you won't be billed twice. If you somehow are the amount will just sit in your account until next months bill.
You'll need to contact Optus directly (livechat) to sort the issue though.