Bookfunnel: Error linking to my Constant Contact account

Hello. I have used Bookfunnel (for ebook giveaways) for years and have it "integrated" to my Constant Contact account. Subscribers to my newsletter get free books.

Recently, the link has not been working. Very bad for business.

I tried to reconnect my CC mailing list/account to Bookfunnel, but I received an error message:

Error integrating Constant Contact: Error retrieving mailing lists: The Mashery account associated with this request is over its rate limit quota.

I checked my website traffic & Constant Contact landing page, and I check the traffic through to my Bookfunnel account. I'm seeing a normal amount of activity on both (a few hundred clicks a week).

How can I fix this? Does not seem to have anything to do with activities on my side.

Thanks.