Ah, but does that really matter?
I've no experience with such things but were I to instruct VISA not to pay a charge which I dispute in writing I do not think they will try to decide whether or not my objection is too "subtle" fo obey: rather they should just honor my request as a card holder and not pay it, forcing it to the next level.
If in fact they do engage in some sort of evidence weighing at the beginning I'd be shocked.