[MENTION=6668855]marciovicente[/MENTION] No, I'm saying experienced wizards likely know the Charm spell merely guarantees the victim's disposition will be "Friendly" for a few minutes, so would undoubtedly weave it into their otherwise normal sounding/appearing verbal discourse about the issue, using their available social skills (represented by bluff, diplomacy, and perhaps knowledge(whatever) to both further obscure the casting and guarantee the victim's disposition becomes "helpful" .... at which point one could reasonably argue the victim was so completely bamboozled by the verbal exchange they failed to notice the Charm's casting and thus later only recall the party successfully argued their point, thereby changing his mind.
The victim remains fully aware of their surroundings (excluding the actual Charming unless informed of its casting/useage) and since this circumstantial bonus expires with the spell, their disposition reverts to its original level, adjusted according to the group's subsequent actions.
That said, the new information "They started to fight. At the second round, the wizard casted Hold Person on him. Then, the Charm" indicates the victim's original disposition was "hostile" and would become so again once the Charm expires.