Not air asia but Thai airways, i changed flight date 2 times, first time easy on my Thai phone app, unbelievably cost 30p !,. second time you can't do it on your app and your advised to telephone thai office, well we all know that means a long wait on phone, so i go on thai facebook messenger page and do "autobot" thing on there, worked like a treat, cost me £75 this time, and you don't get charged untill few days before your flight,. On both ocasions i got confirmation emails imediately ,."TOP TIP,." when changing flight dates try a few different dates and you will get a few different prices, mine varied from 30p up to £200+,.
I,m emphasizing the point that not everyone is computer savy,. so yes you supply the visa company all your information, but they do all the online application part of the process,.its ok for the many people who are good on computers, but for the ones who aren't so good they have somewhere to help them,.