Oil leak - mechanic 'fixed' something else

Please help. I bought a used 2006
Volkswagen New Beetle with tiptronic a
year ago. I had it inspected at a
Volkswagen dealership prior to purchase
and they said it had a small oil leak coming
from the vaccum pump. I purchased the
vehicle and noticed that it dripped
approximately 1 drop of oil every day. I
took the car in for an unrelated repair two
weeks ago (interior light issue) and the
mechanic I took it to noted the oil leak. I
said yes I was aware of it, told him that the
pre-purchase inspection had indicated it
was coming from the vaccum pump, and
asked him to tell me what it would cost to
fix it. He said they would check it out and
let me know. He came back and said I
needed to replace the oil pan and the oil
filter and said it would cost over $900.00. I
agreed to the repair since I don't know
anything about cars or oil leaks and paid
for it. A week later I noticed new oil spots
in the same spot on the driveway. I took it
back to the shop and the mechanic said
there must be another oil leak that needs
fixed. He changed the oil filter (again), put
in some dye, told me to drive it 100 miles
and bring it back for inspection. I suspect
the he originally misdiagnosed the oil leak
and replaced stuff that didn't need
replaced but I have no idea how to prove
that.  So of course now he wants to charge
me to fix this 'other' leak which is what I
asked him to fix to begin with. On top of
that, the car is now leaking more oil than it
was before. Before I would see maybe 1
drop of oil per day, now I'm seeing 3"-4"
spots - I took a picture of the driveway
where you can see a YEAR's worth of
small drops and then the most recent,
much larger ones. I don't know what to do.