I recently experienced poor service on a BD C-class ticket. I would be grateful for any thoughts as to whether this is worth complaining about and if so, to whom I should adress my complaint? I was unable to check-in online or at the self-service machine, presumably because I had onward flights with SK. At check-in desk they were also unable to give me my SK boarding passes or check through my luggage to my final destination necessitating me a wait for luggage and a visit to flight connections centre at LHR. On board I sat in my seat and encountered a large lump of wet chewing gum under the armrest which was quite unpleasant. There were at least 4 flight crew being ferried to LHR occupying business seats; they were offered sandwiches first and by the time they arrived at me I had no choice. The sandwich available was unsuitable for dietary reasons so they offered me an alternative from the economy trolley. Given earlier threads on same issue I thought this was nice of them until they had the audacity to charge me 3.50 for it, not wanting a scene or the embarassment of returing it I just paid up. Arriving at LHR, we were let out a central door via a stairway so no priority deplaning for C Class this time. The bus took us to luggage reclaim which is outside secure area for connections so I needed to go through the outside underground walkway to T3 SK check-in followed by security all over again. Is this service cause for complaint or am I just overeacting to a series of small issues?