Ok, I'm pretty sure this problem's been unattended, so I may as well bring this to your attention.
During the instance quest, "Late Charges", I tried speaking to Luigi Vandalo in the Villa Vandalo in Valencia's Florenza, but, when I was about to finish my conversation with him, the Vandalo Guards show up and interrupted the conversation before I could even finish, but I was nowhere near them.
Later on, I repeat the conversation to quickly update the instance's quest goal, which wasn't updated when I got interrupted by them, making it look like I have to fight the Vandalo Guards twice before completing this instance, but in truth, the conversation should only finish without interruption, then the Vandalo Guards can be only defeated once before completing the quest, no more.
Bat Masterson, I've been through this before, and that bug, among many, was not corrected upon Valencia II's launch, as my memory greatly recalls. Please take a look. I really hope this gets fixed soon.