Enable Restrictions on iPhone/iPad/iPod to stop App-Purchases

You got a SMS that this amount has credited from your credit card no. in App purchase & later known that your brother/cousin or any other family member had spend money from your credit card on Apple App-store.

Solution

You need to enable Restrictions also known as Parental Controls, to stop this

Tap on Setting App
Go to General & tap on Restrictions
Enable & it will ask you to set a passcode
Just enter any passcode twice to set it (Don't share this passcode with people you don't want making in-app puchase)
Once the passcode is set, Slide the In-App Purchase slider to off

Now don't worry about misuse of your credit card. Let your cousins play games or watch movies on your IOS device

But remember don't share the restrictions password with anyone.