Brian,
Looks like the alternator is not recharging the battery. When you hear the clicking sound the starter is not getting enough juice. I would check for a drain first to see if something is discharging the battery when the car is sitting. If all is well you can test your alternator output, but the problem is usually the voltage regulator and brushes on the back of the alternator. An easy $25 fix on most earlier models though I am not sure if your car uses the same alternator as mine.
hope this helps.
m

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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)