Yep its very hard, my wife wouldn't take no for an answer, the branch managers are unable to make a decision and leave it up to head office in Bangkok. It can be done but you will need to shop around and have a wife that knows how to sort them out.
Good luck with that, because your wife is from SE Asia she will be red flag as not to return, so you will need to prove that she will return, you will need to show employment and income, a good way is to use an agent for you might have to make up a story for they don't like the truth. Another visa is the sponsorship visa, good luck with the application and I hope it works out so she can visit.