Business visa

"- with a 1 year business visa, do you have to do 4x3 months extensions or no extension just 12 months?" ----- No extension, just 12 months. This is 1 year multiple business visa. You can enter and exit Vietnam any time you want within 12 months.

"- I m currently in Bangkok, how to apply for this business visa?"  ----- You need to apply for a visa approval letter online. Once it's finished, you will receive a scan of it via email. You need to print that letter out, show it at the airport, pay stamp fee of USD 135 (stamp fee for 1 year multiple visa) directly to immigration at the airport to get your visa stamped there.

Another way is that you also apply for a visa approval letter online for 1 year, but request a fax of this letter to Vietnam embassy/consulate in Thailand. Then you print the letter and fax document out, bring them to the embassy/consulate, pay stamp fee to get your visa stamped there.

Just came back from a stay in the US.  Bought a business letter and sent it and the required funds to the VN embassy in DC.  When I came through Tan Son Nhat, I realized (after I came home) that they stamped my passport for90days.  I contacted the woman I hired to get the business letter.  She says DC made a mistake...first time ever she say.  But for another 270usd she can fix it...and oh be blessed, she's losing 70usd on the deal.  Anybody have any suggestions on how to get this sorted out?