Purchase AWS Credits

You can use AWS Advance Pay - see here for how to use Advance Pay: https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/manage-advancepay.html Please note that there are some restrictions to using Advance Pay: https://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/billing-limits.html#limits-ap

Very unpleasant. Maybe there is a (or many) reason(s) for not allowing direct debiting cards in Advance Pay. But when you want to add some credits into your AWS account and forget about it 6 months.. you can't