Why would I waste time chasing a merchant down to do manual login when I can clearly see the statements were manipulated or altered (either visually or via a third party program like Decision Logic or Plaid)?

It doesn't matter if the merchant or ISO altered the documents. Quite frankly, you'll never get an honest answer from either of them; the ISO will blame it on the merchant, the merchant will blame it on the ISO.

I just flag the merchant and move on to deals that can actually fund.