It is not uncommon to find problems with reports, especially if you have a common last name. If you find a problem, start with the reporting agency to clear it up. It is common to have a late payment at some time or another. These problems can usually be taken care of with a letter of explanation from you to the lender. Loan brokers work for you and have a fiduciary relationship.
Most banks cooperate with loan brokers.
You can go to a broker and obtain a loan through a bank. Most banks will offer you a menu of programs while a loan broker will offer a menu of lenders. Banks and loan brokers are under different government controls. A complaint regarding a bank would go to the State Department of Banking. A complaint regarding a loan broker would go to the State Department of Real Estate.