Is it legal for companies to share customer details?

I wanted to ask whether it is legal for a company like brokerage advisory, credit card banks, or other such companies to share data of their clients without their permission, with other companies and that those other companies call the clients everyday disturbing them any time of the day without the clients permission? I once registered my mobile number with one epic research brokerage advisory firm for a trial but they insisted on subscription of paid services and even after my refusal they continued calling everyday to change my mind and purchase their paid subscription. To so much extent of disturbance that I have to block their numbers because they would call me from new mobile numbers or telephone numbers. And after some time I started getting calls from other brokerage advisory firms whom I never contacted. Recently I talked to one of them and asked who gave them my number and I was surprised that they told that since you registered at one such advisory firm they got my number through data exchange. I never expected that my numbers would get forwarded to multiple advisory firms and that their marketing team will start calling me everyday. I wanted to know whether there is any law against such unauthorised sharing of data and contacting through telecalling without authorization ?