trust me that they never know how to check your screen!
my experience for the past whole week:
2nd Aug - sent in for yellowish tint issue
5th Aug -Morning- received sms to collect phone - Noon -collected, screen replaced, but only done minor checking on the spot to make sure yellowish tint is gone - Evening- reached home from work, playing the phone with light switched off at room, the screen automatically tuned to lowest brightness, then some small white circle spots appeared in the middle and top right corner of the screen
6th Aug - Sent it back to samsung, the reception told me there was no technician that day so can't explain why is it appearing. But they have made clear notes on the job sheet stating all my problems.
8th Aug - after various phone calls to samsung 1800, the berjaya technician finally call me and told me this:" Mr., I don't see anything on your screen wor"

they indirectly forced me to drive all the way down to plaza berjaya from sunway area just to show them those spots. At first they still try to deny there are spots around, but after showing them various pictures from various source - google etc. They finally admitted there are spots and agreed to change another screen for me
until now I haven't receive SMS telling me to collect my phone

I bought the phone for three weeks, used it for two weeks and one weeks is with samsung service centre

dude i have to say u r very unlucky...