Thank you for reaching out to the Constant Contact Community. It's my pleasure to assist you today.
That's a great question. Any billing question for Google Ads will be handled directly by Google, however, you can access your Google Billing by going to Campaign Details and then down to the Manage Billing in Google Ads button.
If you need further assistance, you may reach out to Google billing. Thank you for using Constant Contact and I hope you have a great day!