you are the virus. Yes people like you are the virus! The world needs rid and you should have stayed in the hole you just crawled out of to make that comment.
go to the Bangkok expats Facebook page and ask for a reputable agent there. Someone will recommend someone that has been used before. If you were in Phuket, Chiang Mai or Pattaya, I could recommend someone from personal experience.
SHA plus packages have to be paid in full, you cannot pay on arrival. Only then will they give you the confirmation certificate that you need to register for the Thailand Pass.