My father has a very common name and he was charged with $7000 in credit. However, we know this isn't him because the social security number is wrong and he never applied for any credit cards. Now a law firm keeps sending us notices and threatening that we have to pay the money or else they will put a lien on our house and my parents' paychecks. When we call the law firm, the person was very hostile and kept saying that we need to pay the money, even if it isn't my father. I was wondering what we are supposed to do now?