I asked the merchant guy for the bottle of wine and he asked me to burn the cart which I refused, and then I got him arrested and then took the bottle of wine from his room. Now I have the bottle of wine in my inventory but the quest for it isn't marked as complete! Is there a way of fixing this?

Edit: ok, turns out you can open his trade window and simply buy the bottle from him, which marks the quest as complete. You can still talk to him about it and he would still talk as if he has the bottle and would offer you the quest, in which case you can refuse, get him arrested, which will make the bottle disappear from your inventory and appear on the floor in his room. So that way you can finish up both quests without glitches....