Just tried to change the dates on a flexi saver ticket and was told that I would get hit by a USD 50 charge (in Jakarta).

Is this some new thing that SQ has just started slapping onto people to try and dredge their accounts out of the red?

This was one of the main benefits for me of actually picking to fly SQ over other airlines was because there were no charges normally associated with changing dates on the tickets, particularly in creating a stopover in SIN.