Unfortunately, the stock camera in Lenovo P700i doesn't allow you to turn down the shutter sound using the up and down volume buttons, instead it adjusts the call ringer tone and that's hardly what you want when taking pictures right?
Here's the easiest fix i got:
Download Camera ICS+ here or go search somewhere else if you want. It will let you use the volume buttons to adjust the Media Sound (which controls the shutter and also game bg sounds). It's a 3rd party camera but the UI is entirely like the stock ICS camera so i had no problems adjusting. :D
Another option is to root your phone and locate the camera shutter sound file, something like camera_shutter.ogg, then delete or rename it so it doesn't get called in every shot. But of course, rooting the P700i is a painstaking method so i don't really suggest it. This was my first option though, before i realized that the shutter sound is a Media Sound and whenever i play games and lower the volume, it also lowers the shutter sound with it haha. >XD
Problem solved (at least for me) ! Hope it works for you. >:D
If you find this solution helpful, please do comment! :D
on the other hand, still crossing my fingers on a non-root solution for the same problem on the Lenovo A60+ though haha >XD