Maria - I had a similar question on this forum many moons ago, but didn't receive a reply. In the past two years, I started conducting some ACH audits. Before that time, I never knew much about the process. I have learned that the folks returning these items are usually not the same people who handle Reg. E error resolutions for debit/ATM cards.
ACH error resolutions covered by Reg. E fall in the following categories:
1 - R07 Returns - Authorization Revoked: These are typically the internet service provider, the tanning salons, gyms, etc. that customers join and then later quit. When the companies continue to debit their accounts, they sign an affidavit at the bank stating that the authorization to debit their account has been revoked and the bank returns the item R07.
2 - R10 Returns - Unauthorized: The customer signs an affidavit that the third party was never authorized to debit their account.
So far in my audits, I've observed that banks simply get the affidavit signed, initiate the return, and refund the money - end of story. I've not seen anyone state that the credit is "provisional" nor have I seen a "final" follow-up.
Reading the ACH Rules [OR Subsection 5.1.7], an ODFI (originating bank) has up to 5 banking days after the settlement date of your R07/R10 return to "dishonor" it. Perhaps a bank should state that the credit is provisional as of the date of return and once the deadline for dishonoring the return has passed, notify the customer that the provisional credit is final.