Just got done talking to world perks supervisor and she said the 20,000 miles would be restored, explained it was a computer error and apoligized. I asked for compensation and she repeated 3 times that compensation was not possible in this situation. I then called NW customer relations's number, and after a wait of 20 min. (which I had to pay for) they said they would resgister a "formal" complaint and gave me 5,000 world perks points.

Am happy about that . The moral of this story is persistance and READ your world perks written statement closely.