Holding a redemption tkt in J booked during Krisflyer promotion. SQ changed my flight schedule and rebooked me. They sent me an email asking if I accept the change or not. I rejected it. Called them asking to change the date. Agent is charging me double the miles because "the promotional redemption rate is not available on the new date. How is this legal? The carrier cancelled my flight and rebooked me on the next available one. Why should I have to pay any fare difference, whether its revenue or redemption? What am I missing?