Accidentally booked a stay in Shanghai over 72 hours

I accidentally, stupidly booked my flights through Shanghai for a stay over 72 hours. Flying from LAX to land in PVG on the 10th, leaving to BKK on the 14th. I meant to leave on the 13th. Tried to change the flight but it would cost $2000 to do so, more than I can afford. What are my options? Are there any exceptions made, could I just stay the extra day if I notify the airport upon arrival?