First off thanks for the advice on bus 6005 for Centermark in Myeongdong, The stop was right around the corner in front of Aventree. However when going back on a Sunday, there was no bus. There were a few of us from Centermark and we were not impressed that our hotel did not have the changes noted. I suggested to one of my fellow travelers to go into the Aventree lobby. That hotel gave them a sheet with an alternative airport bus 5 minutes away. Of course we missed that bus and had to wait for the next one. Also note there seem to be a lot of protests in Myeongdong and as protests have to be authorized by permit with the police, there is common knowledge of these events. When I was getting on the bus at Incheon, the guy almost did not let me on due to this (my stop is at the end) but the bus driver said ok. It turned out there were none around my hotel.