What is currently the best Phnom Penh agency for getting Thai visa?

In Cambodia it has always been better to go through an agency than applying yourself for a TV.

In the past there have been some travel agencies that were able to provide double entries while most could get you only singles.

Now,that the double entries are a thing of the past, my question is which agency is best for getting a single for somebody who has already a couple of stamps in his passport.Somebody mentioned Ana in Sihanoukville the other day.How about Phnom Penh, or possibly Siem Riep or Battambang.