Bring any mortgage statements or other documentation that you believe shows the error that was made. If you have written a notice of error to the mortgage company, bring a copy of that letter. Bring any late payment, default or other notices your lender may have sent. If you spoke to someone from the company on the telephone, bring any notes you may have made about the conversation and result of it. Basically, bring any information that you think shows the error or errors, any attempts you have made to resolve it, and any communications from your lender