score:6
AirAsia shut down all their call centers in 2019, all support is now exclusively online. The main channel is their "Virtual Assistant" AVA: https://support.airasia.com/s/?language=en_GB
Obviously it's a bot, but it can also transfer you to a human agent if needed, and that's probably your best bet. For your particular scenario, at last check any requests to change existing bookings are automatically connected to an agent.