If you lucky, they will email you stating something wrong with your credit card, ask you update and order will continue.
The cancellation email looks like this.
Your Google Order #xxxxxxx with Google Asia Pacific Pte. Ltd. is currently on hold. An attempt to charge your MasterCard-xxxx for ¥179,200 JPY failed. This may have occurred because of insufficient funds, or as a precautionary measure against fraud. You may see authorizations on your billing statement for a declined charge. Occasionally, the authorization for a charge may be approved, but the actual charge for the order declined. Contact the customer service department for MasterCard-xxxx for help with resolving this payment issue.
If you'd still like to receive this order, make sure to update your payment information in your Google Wallet account, rather than placing a new order. If you place a new order with updated payment information, any pending orders will resume automatically. If valid payment information isn't provided within 7 days, the order will be cancelled. Update your payment information at https://wallet.google.com/updatePaymentMethod
Once you've updated your payment information, you can verify that your order is processing by reviewing your receipt at https://wallet.google.com/
The cancellation email looks like this.
Google Inc. has cancelled your order. You have not been charged.
This order was likely canceled for one of the following reasons:
Details provided for your credit card do not match those on-file with your financial institution.
The address information provided was incomplete and could not be verified.
To block an attempt to purchase more than the maximum allowable devices.
Please visit Google Wallet to verify or update your account information. Be sure that your full billing address is complete and matches those on file with your financial institution or credit card company.
For further information, please visit our help center, or call us at 1-888-4UNEXUS.