Hi Sree,
Sorry to hear you haven't gotten your OL yet. As VYLE said above, it is quite likely that your OL might take longer, as the federal District Court has to first approve your name change and then schedule your ceremony. I did not do a name change, but the District Court with jurisdiction over my residence has retained the exclusive right to perform naturalizations (which is why I couldn't have my oath on the same day). Even so, I was told if I did not hear back after a whole 3 months, only then should I contact the DO. So, I don't think what you are experiencing is unusual--although it can be very frustrating...
It is my understanding that once you get to 60 days past your interview, you can call the NCSC and initiate a Service Request to "prod" the DO. You can also schedule an INFOPASS at any time, though you are not likely to get very far with that. By law, USCIS has up to 120 days to decide your case after the interview. If they go past that, you can technically file a lawsuit to force them to make a decision. You can also contact your congressman and/or senators and ask their office to help (but from what I read on the forum, they are not usually willing to help until it's been 120 days).
I know you are very frustrated with how long this is taking... and I hope you'll get your OL before too long without having to go to these lengths. I was fully prepared to fight USCIS at every step after the 3-year delay in my green card process and was surprised that, so far, I haven't had to do so.