ok folks here is another trick I've seen months ago:
"There is a post here on SQTalk about SQ and how and when they clear waitlist. It says something about one SQTalker who went to the ticketing office at the airport to check on his waitlist status, and this triggered (??) the confirmation of the seat...
Well, after reading this, I went yesterday to the SQ Centre in Ion Orchard. My Suite redemption was on waitlist since 1 week for a flight this coming Friday, 4 April.
It lasted 3 minutes, I told the lady I love SQ, I love SQ Girls and that I would love to fly Suite on Friday She said she would write a note in the file about my request.
This morning, SMS received, Suite confirmed
Not sure if it's possible to draw a conclusion out of it but for sure, next time I'm on waitlist, I'll pay SQ a visit !"
Source:
http://www.sqtalk.com/forum/showthread.php?t=12443&page=9 Please keep us posted if anyone tries this.