This question already has an answer here:
So long story short, someone managed to cross thread one of the seat rail bolts while removing and reinstalling the seats. They then simply tapped a larger hole and used a larger bolt to fix the problem.
I would like (purely out of OCD) to go back the factory bolt. How do I make the hole the correct size again? And also, anyone know what the specifications are for the seat rail bolts on a VW Polo 6R?