Concrete Emergency Please Help

My wife and I have a very unusual situation. A plastic bottle of a "Cactus Food" tipped over and sat in the solution for a day or so. It
is a slightly low spot of our concrete patio so it did not evaporate as quickly as it might have on an area that did not "pond." The solution is comprised of the following ingredients:
1.0% Nitrate Nitrogen 7% Available Phosphate (P 2 0 5) 6.0% Soluble Potash (K20) 1.0% Calcium
Derived from: Ammonium Nitrate, Calcium Nitrate, and Potassium Phosphate.
What has happened is that it has stained our concrete patio, and where the bottle had layed down, it has etched a groove in the surface of about 1/2" or so. When we called the company they took no responsibility, in fact they were rude, saying that this had never happened before and it was impossible. My wife talked with someone in a concrete manufacturing company who said this type of solution could damage concrete. I did not know where to turn so I am curious about what you folks in the chemistry community might think of this. Also, it is odd. Since this has happened, every morning the area where the spilled occurred appears wet, even though it is not currently raining. It almost looks like moisture is being leeched out of the air and drawn towards this spot? The person in the company did tell my wife to drench the area with bleach, but that did not help at all. Any idea, suggestions, etc. would be greatly appreciated. We do not even know who to ask to help us as we do not want the concrete to degrade now that it has been deeply etched. Thanks in advance for any help you folks can offer.
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