It is only 30 minutes to reach DDR to BDTS. If you have enough time, buy local tickets, else skip this step. Do not waste time with Auto Rickshaw. They are nasty. Board local at DDR (WR) in the first coach in local going towards Borivali. Get down at Bandra and in front you will get a overbridge which will take you out of Bandra Station on East Side. BDTS is hardly 200 meters from there.