I fill up my Bora (Jetta A4 in USA) every 5–6 days so anything to reduce my time at the petrol station is welcomed. When you fill up you will see the dinodiesel bubbles up the fillerneck and clicks off pump.  Leave it for a few seconds and the bubbles subside letting you put more fuel in. 
My normal trick is to hold the vent button with the delivery nozzle when getting close to the top, this reduces the bubbling effect. VW put a little device in the filler cap to stop overfilling a PETROL tanks but don't bother removing it for the diesel variants. When the cap is replaced it equalises the air pressure at the top of the tank with the filler neck. This is a complete pain the behind and useless for the Bora which is diesel. After stumbling across it on www.tdiclub.com  I decided to do a Ventectomy.

I cannot find a “how to with photos” on the TDIclub website so here goes.
Photos are from TDIclub

Tools needed:
T20 Torx bit.
Flat blade screwdriver.
Up to 10 minutes of your life.

1) Open petrol cap and unscrew the one screw holding the door in place

2) Remove screw petrol cap and rotate complete door assembly out (it just falls out)

3) When removing, the drain tube will come with it, this normally just hangs downwards and does not clip in anywhere.

4) The vent button is held in place by one clip designed into the vent. Push this up and push the complete vent assembly away from the filler neck. This will be tight and may take some force.  Some people use 2 screwdrivers to get enough leverage. To gain better access you may have to remove the latch (left side of filler neck).  This is held in with the Torx screw which you have already removed so just wiggle it out and you can't go too wrong.

5) Remove the vent button from the holder.

6) Reassemble all parts in reverse leaving out the vent button.  You must install the white vent holder or diesel will spill out everyhwere and expose the fuel to outside air..

On the next fill up you should be able to put another 5-10 litres without any problems. It will whistle slightly when it fills up, this is completely normal.

Disclaimer- VW put this valve in as standard, if you choose to remove it is YOUR DECISION.  For more advice look on TDIclub.com or get in touch.