I have no advice but I was wondering as a kind of new DM: how did the charming go? Did you roll a save in secret? Did you just tell the player his character got charmed? What did the rest of the party see (players and PCs)? Does the player know his character is charmed and just choose to follow along even though it's bad for the party?
I asked the bard to roll a Will save. Everyone saw how much was rolled. and secretly sent him a message on Facebook that he is charmed. Later I asked the Druid and Fighter roll also. They rolled a successful save, but I still told them to check their facebook message, where it was written "all is OK". So, none of them actually know what happened, but based on bards actions they feel something is fishy.But... I am also a new GM - it's been like 3 years and we have gotten only this far :D