Maintenance Dues for Common Area & Holding Charges

I own a 3BHK flat at Bhiwadi in a society developed by a renowed builder. Builder offered the fit-out possession of the flat in Feb 2014, till 18th May the essential work like sanitary fitting, seepage issues and other work was not complete but even then we signed a paper to get the possession to start the fit out work subject to completion of the remaining work. Meanwhile the maintenance activities of the common area was handed over to the 3rd party service provider for its maintenance. That mainteance service provider is asking for maintenace from 1st April 2014, while we are ready to pay from 18th May, 2014. Are they justified in asking the mainteance from 1st April, 2014 and would not issue NOC which is a pre-condition for getting the property registered (as asked by the builder) and builder is asking for holding charge @ Rs._____ of the super area of the property from the date of offer of possession or not getting the property registered from the date of offer of possession. Is builder justified in asking for holding charges. if you can reply with the remedy.