We have had some erosion around our foundation, and were told by a local foundation company to fill the holes with sand. The sand/dirt company that I called said this was very much against building code. Who is right? (We have fixed the erosion problem with gutters).

Robin,
Contact your local building code department for the town in which you live. Every area is different so nobody here can give you the correct answer.

Reading over the problem again, I would fill the area with dirt with a 1 inch per foot slope away from your foundation a minimum of 6 feet. Sand will allow the water to penetrate down along your foundation walls, which is what you are trying to avoid. I apologize for the first answer.....