If a customer indicates that the Pre-Note to an ACH transaction is not correct and wants it stopped, should we track these situations as we do our normal Reg E unauthorized transactions?

A prenote isn't subject to Regulation E at all because it's not a transaction to or from the consumer's account. That said, you should heed your customer's request that transactions from the Originator not be posted. I suggest you get a statement in writing from your customer that the transactions aren't to post. Then prepare to return each of the dollar transactions as unauthorized.

Thanks John, since the time I posted I had a little while to think about it, and concluded as you said.....prenote not subject to Reg E. But again, thank you for your confirmation.