Three things might have happened:

1) The tubes are trapped or kinked in the bonnet hinges
2) The filter to the pump is blocked
3) Or the pump itself has failed

You can check the first thing yourself. You can probably clear any gloppy debris from the pump filter by shoving a hosepipe into the bottom of the washer reservoir and blasting the crap out. If that works, add some Milton baby bottle sterilising fluid to the washer fluid to prevent bacteria forming. If none of this works then the pump has failed and needs replacing. But completely bonkers to pay a Volkswagen dealer £80 or more for electronic diagnostics when a new washer pump is less than £20.