recently i installed custom rom in my galaxy s4 gt-i9500 and now i am facing problem like imei changed to 0040**** and network not registered problem. i already tried lot of lot of options and solution to fix it. like flashing different official firmware, upgrading and downgrading baseband version.

sol plzz i need help to fix this.
and i know it is software problem regarding to efs folder that contains imie data and information and which means its not a hardware problem.

so plz tell me how much does its cost to repair this problem. because i need to repair this as soon as possible.
thank you..