A subscription payment may fail if your available balance is below the subscription charge.
For example, your available Zip Pay balance is $10 but your Netflix subscription is $14, the payment to Netflix will fail and your available balance will remain at $10. The Zip card will then become invalid.
To ensure your subscription is not cancelled you will need to top up your Zip Pay account by making an additional payment.
Once sufficient funds are available in your Zip Pay account you will need to generate a new subscription card, copy the card details and add it to the subscription service.
From there a manual payment to the subscription service will be required, this can be done using the newly generated Zip card.