Another update:
I went to post the complaint letter today at my local post office, but the usual employee who knows me, and is aware of non-delivery of mail at home wasn't there. I think he has been transferred to another post office. The new guy refused to accept and send my letter addressed to my area's postmaster saying the person in question will lose his job etc etc. All that time when he was saying that, I was thinking the postman isn't even doing his job and this guy is claiming he'll lose it. He said I should go to the GPO myself and talk to the concerned postmaster face to face.
I posted the letter via TCS though. After I posted and came back home I got a call from TCS guy claiming that he has lost the letter and whether I took the letter with me after payment. I obviously did not. I went back to the TCS center and when I reached, the guy told me he had found it.
I am not sure what is going on..