Visa exemption

Hello,

I'm spanish citizen and I have a visa exemption to travel to Vietnam within 15 days.

My question is: Do I need a flight ticket back or any other transport ticket to proof I leave the country before 15 days?

I want to cross the border to Laos by foot or maybe buy a bus ticket once in Hanoi, in case I need to prove it, how can I?

Air Asia told me I need this ticket and didn't let me took the flight I bought to Vietnam? Is this legal? Can they do this?

According the Vietnamese Resolution No. 46NQ-CP there's no need to proof this go-back ticket.

Can someone make sure is this right?

Here the link of the Resolution.

http://lanhsuvietnam.gov.vn/Lists/BaiViet/Bài%20viết/DispForm.aspx?List=dc7c7d75-6a32-4215-afeb-47d4bee70eee&ID=64

Here official notice of the new exemption visa list of the Vietnamese Government:

http://news.chinhphu.vn/Home/Visa-exemption-for-five-nations-in-Western-Europe/20156/24613.vgp

Thank you so much.

I'm currently stuck at Shanghai Putong airport because of this. So I would appreciate a quick answer, as soon as possible.

Best regards,

Jordi