I would still keep the fans in mind.
There is an internal fault in the module that controls them (it's actually part of the fan assembly). This can sometimes short-out internally, causing the fans to run on, and drain the battery. I've also seen one where the fans weren't actually working, but the module was still pulling enough current to flatten the battery in a matter of hours.
Other things to consider are the condition of the alternator, any aftermarket or non-original accessories (the radio unit for instance; perhaps upgraded from the standard one?), and the condition of tha battery itself. Just on the alternator itself, the pulley has a one-way clutch on it, so-to-speak. Spin it one way, and the internals of the alternator will spin and charge the battery. The other direction will not. Occasionally, these fail to the point where neither direction will allow the alternator to charge the battery. Easy enough to test with the car off, and the belt removed, and locking up the alternator and testing which way the pulley spins. If it spins freely in both directions, it's no good.
For the DIY-ers, this method is the easiest, and least-intrusive way of testing on a modern vehicle:
A new approach to testing parasitic draw | Search Autoparts
And here's a link with charts that compliment the fuse you're testing, and the reading it should have:
Fuse Charts Download
'07 Transporter 1.9 TDI
'01 Beetle 2.0
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