Nokia
Not replaceing my defective moble

I bought my Nokia 6300 in jan 09. from starting it is having a problem of getting restarted during the calls or messaging. I have shown this problem to nokia care here in Bhopal 5 times... they always say it need software updation or some other n give back to me..but it is repeating again. i have requested to replace but they r saying we cant replace it as the prblm is not major. Please help me on this