wrong calls and smses

dear sir/madam,
kindly guide me on how i can take legal action on the above mentioned company. this company (shriram finance) is wrongly calling me up again and again and sending sms about outstanding loan against gold. i have no such gold loan with them and i have informed them time and again. however i keep getting their calls and smses about the outstanding loan.
i wish to take legal action on them now for causing mental agony to me. hence kindly guide me on how i can go about it.
thanks
sanjay jagtap