Play Store updates downloaded on 3G network by ignoring settings On my Xperia J phone Google Play Store setting of automatic updates is set to: Wi-fi only.

To my greatest surprise, yesterday it started to download 50MBs of updates when I was on 3G and my 200MB package was almost exceeded. 

I checked the Data usage of Google Play Store on my 3G network and on Wifi: Wifi has 432 MB traffic, 3G has 82 MB (with wifi-only settings). 

My question is: what settings should I use to prevent the abuse of my 3G package? Have you experienced similar behavior?
If you haven't done so already, try going to Settings - Data usage, then press the menu key and choose "Restrict background data".

This sets all sync functions to only work on Wi-Fi, maybe it also helps with your Play Store problem. Be careful though, if you rely on sync to work even when you are not on Wi-Fi (Gmail for example), this is not the right option for you.