Jobu,
every time you relate your "nightmare" incident, I'm sure your blood pressure goes through the roof. So, a hundred or so times you have related the story, a hundred or so times you have raised your blood pressure, and, all for what?
What I, and some of the other posters, are trying to say is, why harm yourself (giving yourself high blood pressure) just to "have your own back" on SQ? I believe you, you have been offended, but, honestly, aside from "voting with your wallet" is it absolutely necessary to also convert everyone you know or meet to your point of view, that SQ Stinks Big Time?
Bad service can be found in any company, business, restaurant, etc. What is important is, how prevalent is bad service as compared to good, or even, beyond the call of duty, service? I know in SQ of customer service agents, who, on their own time and expense, have carried out various "beyond the call of duty" service for passengers. (Don't ask how I know)
As you said, you have flown many times on SQ, and this is the first bad experience you had. Did you enjoy all those previous flights? If the majority of your flights on SQ were bad experiences then it will be a different story. But, looks like, for you, it's "One Strike, You're Out".
I guess by now you have flown on many other airlines. Can you honestly say, all those flights were absolutely perfect?
May I suggest this, for the sake of your blood pressure, don't actively seek out people to tell your story, but instead, tell the story only to those who come to you for advice as to which airline to fly with? It really serves no purpose (if your purpose is to move as many people as you can away from SQ) because you can not possibly move enough people away from SQ for it to even notice the loss. So, there's no point to keep cutting your nose to spite your face. Eventually, you may possibly even forget the whole incident and put it down to just another of life's bad experiences.