I would try a product called Terro Ant Killer. It contains borax and sweet syrup.
These ants sound like they are the "sweet" ants you hear about. I had them a few years ago. We used this product and it got rid of them.
It does take about a week or so. The key is to use a multi prong approach. Wipe, clean, vacuum and treat. Repeat.
Let me know how it works.
For more information:
Read "I have bull ants, fire ants, and tiny black ants. Is there a green and effective way to get rid of these pests?" a Q&A answered by Richard Heller.