Bad customer care by standardbank

I have received a call from Strauss attorneys who are continuously forcing me to make arrangement of payments with them.They allege that they stand on behalf of standardbank but standardbank did not inform me that they are taking my personal information to this attorneys.This attorneys are rude,harsh and bully .How do I talk to a person who has my information while I m not informed.I made arrangement with the bank to pay a particular amount.They called me to. Thank me for the payment and now force me to make a new arrangement with them.If standardbank have refered the information pls let me know .I m tired of being bul**** by this people pls because they want money .I owe the bank not them .