How Autoship charges work
The system will charge with the credit card if the autoship payment method is set to credit card. If the credit card fails, the system will be set to unpaid for the autoship order with credit card payment. If you have set the autoship payment to Credit Card, it will not cycle through to the Personal Account if there is insufficient funds in your Credit card, it will stay as Unpaid.
The system will charge the Personal account if the autoship payment method is set to personal account, but the system will switch to credit card if there is not enough funds in the personal account. Autoship will not accept any payment methods other than personal account or credit card.