how much does a 4 year cost

Nothing, fiction of VW UK, there is no such thing as a 4 year service.

Replace the timing belt at specified mileage, and other items at specified mileage/time.

If you managed to do under 40k miles in 4 years, the only 4 year item is air filter replacement.

Note you should have had brake fluid replaced a year ago..

Edited 21 June, 201214 yr by dieselV6