Lenovo — Network issue with lenovo k4 note

Address:	Hyderabad, Andhra Pradesh, 500081
Website:	Lenovp

I purchased lenovo phone 10 months back, I am unable to get signals for both of sim cards. It is showing as sim card is empty. When I put that sim in another mobile it is working fine. The problem is with lenovo k4 note. Please suggest me How to resolve this issue? and alsolet me know if any authorised service centers are available to fix this? Can I replace this phone? If so what is the procedure for that...Please let me know as soon as possible..

Thanks