If you are having issues with your bank or credit card provider allowing payments through, you can also test this or force a payment through directly in your customer account. First log into MageMojo.com then go to My Payment Profiles. If you have multiple servers you will see multiple options for each server or service.
Select the appropriate service and on the right side of the screen is a Retry Payment link. Clicking this will run the current credit card for that server or service and attempt to collect payment. You will receive a message indicating if it fails or succeeds, such as in the screenshot below.