I spent some considerable amount of money until I realized that I had to identify the bugs myself. I have not found an exterminator with identification capability. Why should they, because they came keep coming back and back and charge and charge.
Buy a USB digital microscope. The better ones are $100, the others are anywhere from $30 to $60.00 Once you can get an image, send it to your local university, who will identify the picture you send them. Then you have to research how to kill them.
The key to getting rid of tiny black bugs on kitchen floor is first identifying what they are. Check out what has worked for others in this page.