Thank you for reaching out to Constant Contact API Developer Support. My team is here to assist outside software developers with questions about building into Constant Contact's API.
I have escalated your inquiry to our internal Tier 2 support team so that they can follow up with you directly regarding this issue, as the WordPress plugin “Constant Contact Forms for WordPress” is directly supported by Constant Contact and is not a 3rd party developed integration.
One of our Tier 2 support specialists should be in touch within 4 business days. Otherwise, for immediate assistance, or if you’d like a callback/email from them at a certain day/time you can call our support line at 866-289-2101 and reference case # 31291000.
Please have a look and let us know if you have any other questions!