Mike,
Sound to me like you and your client are both at least partly right.
CANT GIVE A NEW/DIFFERENT VALUE WITHOUT DOING A NEW TYPE OF APPRAISAL
Of course, giving a new/different “opinion of value” is an appraisal, but that doesn’t mean you were supposed to start over from square one in developing it. You can bootstrap off whatever work in the original appraisal you think is good. Your client already has that report. No need to repeat anything you agree with. When your review report states which parts of the original that you disagree with and what other sales, etc., you would consider, you have implicitly incorporated by reference, the other parts of the origninal report that you liked.
You are either certifying to the original value or certifying to a new value and using information that is in both the original report and your review report. So, what is the problem?
--------------
IMO, reviewing is more work than appraising, because the client really wants to know if the value is accurate and is likely sending the appraisal out because it looks fishy.