Indian Post And Telegraph Dept Anushakti Nagar Post Office — Non receipt of acknowledgement due

Address:

Mumbai Suburban, Maharashtra

I posted 2 registered letters on 23/8/2011bearing no A 670 ans A 671 from Anushakti nagar Mumbai Post office whereas one acknowledgment due was received on 28.8.2011the second has not yet come back It is an important document as proof of receipt in the court case .can I get it soon.
VSD