Concrete Trimmings

This company did a concrete job at my neighbours house, they were power washing all the cement from the neighbours into my garden where there is a koi fish pond with over 30 fish, we warned them this would kill all the fish with the concrete and chemicals they assured me it would be ok! We asked them to please be careful. Since they have finished our fish are all dying , all the dust and chemicals are on our garden and directly into our pond, they dont return calls and wont acknowledge anything! They have left my place a mess all the steps on the side of the house is full of the dust and chemicals from the concrete job next door. which slopes down to my koi fish pond and all my fish are dying. In order for me to fix this situation i need to drain all the water replace the pipes and filer system the pond liner and essentially redo my pond and get new fish which would be an expense of over $5000. These people have no respect and have let my fish die one by one with poison. Some fish we have had for over 3 years! One fish was bought when a family member passed away so my son always remembers them! This people refuse to answer or get back to us!