Unwelcome guests - is it bugged?

Nick Altman

I am struggling with 61 out of 62 quests in Shadowfen. I miss one to have 62. I noticed that the Mercenaries are still in Stormhold and I think I maybe didn't finish that quest. The merchant gave me the quest, I fought the mercenaries, came back but he was gone. Only a mercenary told me that he left. If the mercenaries are still in town is the quest unfinished?