Buy a digital recorder that can last an entire 12 hour shift. Do what you sincerely think is right and legal and to the best of your knowledge and ability in your job. Do not respond to their provocations. They go beyond what is acceptable, stop the taxi and just ask them to take another. Never challenge them to make a report. Use words like..."Do what you think is correct." And if you can summon it from your inner self, erase them from your mind immediately when you resume driving. Download the entire data from your recorder into a new folder that you had created for this purpose. Delete them after three weeks to save space. If a complain comes in for you to answer, it will be within that period. Best of luck.