Ac in dead wall

Dear Sir, I have purchased a flat in 2003 . The flat is small with one room and kitchen . In 2007 I have made written application to the society in single copy that I may be permitted to make a small window on the one of the wall as my room is very small and there is no cross ventilation . The society members inspected my house and told me that I can make a small window . But they have not given any written permission . I have made small window on the wall that I have proposed and also the society agreed . I have not touched any beams or columns. In 2010 I have fixed an AC on that window without making any changes to that window. The Society committee has changed and now they are teling me to close the Window as it is on the dead wall. I want to know can a society committee behave in such a way that after four and half years they tell me that the permission cannot be given for opening a window in dead wall and the permission and the window is illegal and the wall should be closed. I have gone through the building code but in that there is no reference of dead wall. I am still unsure whether the concept of dead wall exists in the building code. I have seen some other societies in which people have put up thier ACs on Dead walls. Kindly guide me on what legal remedy do I have in this and what can be done . ND