You are an external IT auditor engaged by a multinational corporation to evaluate the effectiveness of its IT controls and governance framework. As part of your assessment, you conduct interviews with key personnel, review documentation, and perform technical assessments of IT systems and processes. During the course of your audit, you encounter resistance from certain departments unwilling to disclose sensitive information or provide access to critical systems for testing purposes.

Additionally, you discover discrepancies between reported performance metrics and actual operational practices, raising concerns about the reliability of internal reporting mechanisms. How would you handle these challenges as an external auditor, ensuring the integrity and thoroughness of your audit while maintaining professional relationships with the client?

Describe the approaches you would take to address resistance, gain access to necessary information and systems, and verify the accuracy of reported data. Additionally, discuss the importance of maintaining independence and objectivity throughout the audit process to uphold the credibility of your findings and recommendations.