Unfortunately people believe visa agents who can easily obtain visas in Thailand by paying "tea money" to immigration officers can do the same for other countries. This is complete nonsense. All the agents here will do is to scam you out of your money to fill in the online form which you can easily do yourself . Like
@Gra***
above I hope you got a full refund from the agent you used. My experience with Australia for a tourist visa for a Thai is you have to demonstrate they have sufficient reason to return to Thailand. Most important is a statement from her employer stating length of service, position and salary. This alone is mega. Add to this bank statements showing good record of saving, any land or property documents showing her as the owner will be the cream on the top. It's not difficult. Since being with my lady (and we're not married, but have a long relationship) we've been successful in getting 3 x UK visas, 2 x Australia and 1 x Schengen. Of course, it gets easier as time goes on as they see she has a perfect immigration record. Work on it, you'll get there