The same thing happened to me once, but airasia email me. In the email, there's a telephone number (Retime and Cancellation Call Centre at +603 2614 2999) and also a password. I called and was informed that I could change my flight plus and minus 3 months FOC. If i'm not mistaken, if the flight is retime more than 45minutes, you can change the flight for within the day. Mine was retime more than 4 hours, so I could change for a within 3 months or get a full refund. I could even change the connecting flight.