I think I overheard when I was at immigration last week there were 8 companies they have on their list. Could be totally wrong. I use Pacific Cross and I submitted it and the officer seemed happy enough but mine was for a Non O. Best to ask immigration their approved companies if in doubt.
I thought it was this post where I asked about my new passport coming back from the UK whilst my Non O is under 30 days consideration but I can't see it now. I got a message from DHL saying my passport is on its way to Thailand, so what is it that I need to get from British embassy you mentioned?
I read about people going early morning to queue up and get a ticket at immigration. What is the latest time or best time to go to immigration? Does it usually quieten off in the afternoons or later in the morning or is it adviseable to get down very early?