How do you unclog a blocked drain in Audi A8 which when blocked spills water into the foot wells from the air vents?

To unclog a blocked drain in an Audi A8, first, locate the drainage outlet, typically found near the windshield or under the car. Use a flexible tool or a wet/dry vacuum to remove debris from the drain tube. Additionally, check the cabin air filter and any associated ducts for blockages. After clearing the drain, run water through it to ensure proper flow and prevent future blockages.