An Assignment of Claim is a procedure used by one creditor to transfer its claim to another creditor.  It is a common practice in the business of debt buying and securitized transactions.  The amount of the claim should never changed based on an assignment.  Ordinarily this does not affect your case and you do not have to take any action.  It only means that instead of owing the debt to Creditor A you now owe the debt to Creditor B.