Oxford Law, LLC Debt Collection Complaint

Oxford Law, LLC Debt collection department,

Credit card Cont'd attempts collect debt not owed Debt is not mine California

I received a letter from Oxford Law , LLC, which claims to represent - - , - on -/-/15. The letter says that there an account # - was open under my name ( - - ) with - - -, and there is currently unpaid balance of $3900.00 associated with the account. It also says that the debt was sold to - - , -, which is trying to collect the unpaid balance through Oxford Law , LLC. On the other hand, I do not recognize the account # at all. I pulled a credit report from - because of the letter. The aforementioned account was not listed in my credit report. None of the accounts listed in my credit report has ever had a single late payment history.