NOKIA 6030 Mobile Handset
Mobile Showing Sim Card Rejeted

I Have Purchsed the Nokia Handset 6030 from Vikhroli. I been using the same for 9 months and suddenly I started getting Message "SIM CARD REJECTED" after keeping phone idel for half and hr or so. I took the Mobile to Ghatkopar Nokia Care center twice and they tried reparing it. but the problem remians unsolved. and I feel Nokia should give me the replacement to this phone as this is still under warranty.