Thank you for posting to our forum!
You are correct that the forum is the manner for those on the free Starter plan to get support/assistance.
It looks like Endicia has a flag on the account so you will need to reach out to them to get a temporary passphrase in order to unsuspend the account. The number to call and steps to follow can be found in the article linked below:
If you still need assistance after reaching out to Endicia, please email the temporary passphrase to us at firstname.lastname@example.org so we can assist in re-connecting the account.