Here's the link to vw. Scroll down the bottom of the page to read about the 8 year warranty on the battery.
https://www.volkswagen.co.uk/owners/warranty/new-car/terms-and-conditions
Shame you did NOT read that link......so I'll repost it &
bold &
underline the relevant sections:-
8 Year High Voltage Battery Warranty
A guarantee for eight years or 99,360 miles (160,000 km) whichever comes first, on all material or manufacturing defects.
Gradual reduction in battery capacity over time is integral to the nature of the component, and does not represent a defect under the terms of this guarantee, as long as the reduction in capacity is not in excess of the value specified for this vehicle in the owner's manual.
The guarantee on high voltage batteries does not apply if the defect has been caused by the battery not being used, handled or maintained as described in the owner's manual. This applies in particular to charging the battery.
With the exception of the warranty term, all warranty conditions stipulated by the Volkswagen Retailer selling the vehicle (pre-requisites, criteria for freedom from defects, exclusions, settlement of claims, entry into force and start of extended warranty term, scope of application etc.) Also apply to the high voltage battery.
The eight year guarantee does not apply to the 12 volt battery. The 12 volt battery is covered by the standard 3 year factory warranty detailed above.