Complaint Review: United Auto Credit

I continually recieve calls regarding payments that arent even due for two to three days. My fathers name is on the loan, so they called our house and acted as one of my dad's supervisors, and asked for his cell number. They then proceeded to harass and berate him at his place of work. They will not give any grace to you if u have to make the payment a day or two late, and they charge me extra fees for "overly late payment." This has to be illegal... Does neone know how I may take action against these people?

Kory
paradise, Texas
U.S.A.