Please make sure you have visa to Vietnam, it is impossible to get a Spot Visa upon arrival.
Visa-Free : Asean (Asian Pacific countries) & European Citizen may be allowed to visa free access (about 15 – 30 days), please double check with the Vietnam Embassy/Consulate in your country if you need to apply visa or not. Passport holder of certain countries can apply online visa through internet.
For more Vietnam Visa information, please Click here
For applying e-Visa, please Click here