system update on gs3
 

Hello I currently don't have WiFi and I need to update the gs3 to jelly bean :-) and it only let's me use WiFi but I only have 4g

Well my S3 went in for repairs so I don't have it to verify this. If I recall correctly, there is an option in the Settings, I believe it's in the Software Update section that sets downloading of software only with Wifi.

Uncheck this and you should be able to download the update via Mobile data.

BTW: I thought the S3 was 3G only.

Hope this helps.