Join Date: May 2004
Location: SIN (LEJ once a year)
Programs: SQ, LH, BA, IHG Diamond AMB, HH Gold, SLH Indulged, Accor Gold, Hyatt Discoverist
Posts: 8,813
Should work, just show proof of your advanced seat reservation payment, state that your seat was inoperable and show boarding pass of where you were seated and SQ will refund the paid fee.
As this was done at check in, SQ should have the info, but better to supply it in my experience to expedite the processing. YMMV.