I know of people who did a 'runner' from SQ and got hounded for their bond but I know of others who went in to the office, put their case in a reasoned and non confrontational manner and had their bond reduced to a fraction of what was owed. As you know, 'face' is everything in SE Asia so if you display bad temper, irritability and try to take them head on expect to lose.
There are lawyers in Singapore who will take SIA on and have won, one that springs to mind has offices on North Bridge road, far end of the bridge on the right. Might be an idea to gather all your paper work and notes, adverts etc. etc. and let them tell you your contractual position in Singapore law rather than how you see it, which may be subjective.