If a Direct Debit fails, you will receive an alert to your email which will let you know the payment was declined. 

The system does not allow 2 consecutive Direct Debits for the same payment so please make a 1-off BPAY payment via your internet banking using the Biller Code and Reference Number supplied in the email.

Once this is made and you have received a payment receipt, you can re-activate your Direct Debit in your payment settings.