With that less information in first post, most likely you're going to get guesses or trolls:
1. Guesses like - " I think you can go to Kalina.." " You can try Fort, if not Kalina.."
Or
2. Trolls like - " The process for obtaining transcript Mum Uni is to apply for transcript at "Mum Uni" .. "
Take some effort to write more about what course, when did you pass your course (before certain year of graduation - you have to go to Kalina campus. the attestation is expensive in that case. I am not sure about the exact year).
Update : As of 2022 : They no longer do this offline at Churchgate as they used to earlier. The entire Transcript and Attestation process (for MU) has been transitioned online.
I wasted an entire trip coming into Bombay from out of town - after reading about the offline Attestation process here on this forum but it ended as a wasted trip when I found out they no longer accept any offline applications. Sharing this update here to help any future Mumbai Uni. applicants save their time and money.