I'm sorry to hear that this is occuring. Thank you for posting so we can help! It seems as though you are experiencing an authorization issue with social share connecting to your Facebook page. In order to troubleshoot you will have to disconnect social share from the social accounts and Constant Contact.
Instructions to Disconnect Constant Contact from Social Media Accounts
Instructions to Disconnect Social Media pages fron Constant Contact::
If you decide to no longer use a connected channel for campaigns, you can easily disconnect it.
Once pages are disconnected log out and log back in to Constant Contact and reconnect Social Media pages using the instructions in the second link above. I hope that helps but if you have any other question let us know. Thank you !