What should I do if the property of Xi 'an Long City Mingyuan International Community ignores the housing quality problems (such as the installation of entrance doors) raised by the owners after the h

What should I do if the property of Xi 'an Long City Mingyuan International Community ignores the housing quality problems (such as the installation of entrance doors) raised by the owners after the house is closed? The responsibility of quality maintenance is essentially the responsibility of the engineering construction unit, and the property only plays the role of a megaphone. When the house was delivered, the construction personnel of the original construction unit were basically scattered, and the maintenance work often failed to find anyone or refused to spend money. This question should be addressed directly to the developer.