My bank statements show a debit of RD every month which I didn't sign up for, please help

I'm fairly young, I don't have a family member that can teach me about this stuff. Not educated in the commerce background please help. My bank statements have been showing a debit of 3000 every month from the past 6 months, it shows as RD. I never signed up for it. I tried to call up the branch's phone but they won't pick up. Will I get my money back immediately if I decide to stop the RD? Is it acceptable for the bank to start an RD without my approval or consent? Any tips where I can avoid something like this in the future?