What if the developer doesn't answer the phone, regardless of the property?

First of all, make clear the causes and responsibilities of water leakage, and make sure that the house upstairs is waterproof when it destroys the ground according to the decoration regulations. Waterproof warranty period is 5 years. Let's see if your house is over 5 years old. Now there are many situations like yours, and you often encounter irresponsible property and developers. But many times, the reason why property and developers don't accept it is responsibility. If the original waterproof layer is destroyed during the upstairs decoration, then the property and developers will definitely not accept it, so you'd better negotiate with the upstairs owners to solve the maintenance problem. If the original waterproof layer is not damaged during the upstairs decoration, you must stand firm and resolutely safeguard your rights and interests during the waterproof warranty period, and safeguard your rights and interests through legal means or the media. If there is a similar situation, it is best to discuss it with the neighbors and solve it together, so as not to be weak. Also, determine the cause of water leakage, and see whether the problem comes from waterproofing or pipe rupture, and be clear and definite. I hope it helps you.