I am Rosie Le, Customer Service Officer of Vietnam-visa.com.
It is our pleasure to e-meet you!
According to Vietnam Immigration department’s policy, the Visa on Arrival is only applicable for travellers coming to Vietnam by air. So that we may not be able to assist you on obtaining your VOA!
In your case, please contact Vietnam Embassy in your country to apply directly!
I hereby attached the contact of Vietnam’s Embassy for your reference: https://www.vietnam-visa.com/vietnam-embassy-information/
Please feel free to contact us, we will be around the clock to help!