[tabifolk]

Not sure about that company, but what type of wheelchair do you use?  Power?  Sometimes it is hard to get on a small plane and since Bangkok and Phuket are close, it may only be a small plane…

Here is a link to how to order help for wheelchair users: https://support.airasia.com/s/article/How-will-my-wheelchair-mobility-device-be-transported?language=en_GB

They have a live chat and call center listed.  It looks like that if you fill out the form, they will contact you.  They suggest up to 48 hours before, but it may be best to do it ASAP!