Delhi Jal Board — wastage of water overflow tank

I am a resident of 9/306 iii floor, sunder vihar paschim vihar, delhi -87. People who live in 9/307, puris they switch on their motor let the water running for hours even the tank is full. I have requested them several times to have motor alarm but they paid no heed. Today also it is almost one and a half hour and the water is running continuouly from the tank. I mean the tank is over flowing since 1.5 hours.
Kindly do something.

Regards