Check if the credit card on file has expired or has reached its limit. If that is the case, please add another credit card and define it as a backup card or contact your credit card supplier to increase your limit.
You may find instructions on how to add another credit card via the link here.
To make another payment attempt, please go to the Invoices section and click on the "Pay now" icon next to the respective invoice. 
Alternatively, you can make a bank transfer and send the payment confirmation to the support@merchone.com email address. This allows our team to assign your payment appropriately and manually update the status of the invoice to reflect that the payment has been received successfully.