Nokia 5800 — Screen Problem

Sir,
i had taken nokia 5800 music express, two months back. After one month i realised that mobile screen has some problem. ie. pixel axis problem. (touch Screen problem). i noticed this when i m typing sms by taking mini keypad. for each letter, some area is there. i[censored] press in that area, that key is pressed. but it is not working in my mobile. after that i sent it to nokia and they taken nearly 3 weeks to correct this problem. Now they returned to me, but still it has same problem.