Worst flight I've ever seen. I bought two tickets from Chiang Mai to Bangkok. This flight should arrived at 21:05. Because of its internal accident of check-in system, we got delayed for more than 2 hours. We had another flight to catch at 23:40, from Chiang Mai to Beijing. But we missed it so we had to change our flight to the next day. The VietJet Air was so irresponsible for everything they had done. They didn't rearrange another flight for us, nor did they cover the extra fee of changing flight. They didn't response email, the telephone couldn't get through, the staff in charge in the bangkok airline didn't do anything for us!!!
This is a horrible airline. Once you book a ticket you are screwed. They list fees on their web site which are completely false. Every rep we spoke to had different excessive fees for ridiculous things, and every time we referred to the published policies and fees on the web site they would say "oh, that's out of date". Call back 5 minutes later and the price goes up again. We felt extorted and humiliated. Wasted hours and hours dealing with them, just to initially think that we were saving a few bucks off of vietnam airlines.
Don't make the same mistake. Avoid VietJet Air at all costs.