Air mass meter failures are common on VAG engines so i would not be too bothered about that. Also earlier models of passat were known to have troublesome suspension, control arms failing etc but I thought that this was under control with later models past year 2000.
Alas turbo failure is also not that uncommon on VAG diesels though normally on higher milage than yours.
Have you had the car from new? Is the mileage genuine? If so I'd just say you are unlucky but remember where volkswagens have finished in surveys like the JD Power ones over the past few years.
Their reputation for relability has plummeted a lot in but Joe public still pays premium money for it. I personally know three people who had to replace gearboxes in 2 bora's and 1 Golf, two had under 50,000 miles on them and the other had 70,000.
Then again I had a Mark 3 golf many years ago and sold it to my brother with 110,000 miles on it. It's now got 160,000 and still going strong. Nothing replaced except normal wear and tear items. It was always serviced on button every 10,000 miles.