Nokia 2760
To bolck my mobile

Hi, This is Prakash Penday i m from orissa but i m living at ameerpet (Hyderabad), actually i have lost or stolen my mobile on 4/3 at 9:10 i have my mobile serial number, and all the documents on that time i m using reliance Sim but when i m calling to reliance customer care i said to me i m not able to help u because this facielity is not available

so plz help me how i will block my mobile