I recieved an email stating I owed $509.45 from a loan with Advanced Cash expert.

This company states I owe $509.45 from a loan.  I dont owe anything and they continue to threaten law suits.  The email someone else received in June is exactly the same as my email only the dollar amount is different.  Can someone stop these people ?  The email states to call Matt Williams at 954-762-7500.