I started my business Van-Again replacing Vanagon drivebelts, and Beetle and
Bus radiators, and sparkplugs in diesel VWs.  :)

If you Vanagon is a waterboxer (which I am assuming it is) then it has no
"drive belt" or what I would assume would be otherwise known as a timing
belt.  The only belts it has are for the water pump/alternator, AC
compressor, and power steering (if you have these latter two options).  All
of these belts are not very expensive or time consuming to replace (you could
do it yourself in less than an hour).
I would probably run away from this shop if they are trying to hoodwink you
and find someone else a little more VW savvy.
Ken Wilford
Van-Again
John 3:16
PS If your Vanagon is a Diesel  or has the Jetta/Golf engine in it, then
forget everything I just said and I will now hide my head in shame.  :)