I never thought I would get paid to update my automatic payment but I guess anything is possible in this hobby.
Here is what the letter had to say:
Upon review of your account, an issue with your automatic payments enrollment has been identified. As a result, your enrollment needs to be updated. Any missed payments could cause the account to go past due and late fees to be assessed.
Please call us at 1-800-347-4918 between the hours of 8 AM- 10 PM Eastern Time to change your enrollment. We will provide a $20 credit to your account when you make the update and continue to use automatic payments, which will be credited in February, 2019.