I'm flying from CHS -> EWR this Saturday, scheduled to return on CO 3065 leaving EWR at 9:45 a.m. Monday morning. I was hoping to be able to fly back on Sunday night instead. They have a flight leaving EWR at 8:05 p.m. Sunday, but since this is more than 12 hours before my original flight time, I assume that they wouldn't let me fly standby ($50) on it, but would instead charge me for a flight change ($150).

I'd be willing to pay the extra $50 for an earlier flight, but no more. I assume that I am SOL on this, but I just wanted to make sure I'm reading their policies correctly.