Was on SQ21 yesterday which departs 0945. Went to the Polaris lounge and then tried to take the bus from C71. Contract workers claimed that they do not provide service from C to B for SQ pax. What appeared to be a UA employee nearby then claimed the bus does not go to B until 1115. Was not inclined to argue with them so I went landside and cleared security again at B. No idea if hiding my boarding pass and saying I was going to A, then asking the bus driver to go to B would have worked (as suggested upthread by someone else)... anyone else managed to successfully do this?