I recently applied for a home loan, but the broker told i need it a higher score for a better mortgage rate. The broker offer to fix my credit and get me the preaproval. I am still not convince that the broker can do this for me.

He can definitely help you with it. A lot of mortgage brokers know credit repair techniques and can advise you and even do the work for you to boost your score. Some charge a fee and some do it as a value added service for free.