Samsung South Africa
Who is responsible for Android updates here?

Hello, I'm sorry to have to bring this up here, but I need to know why updates to android are taking so long in our country. I own a S3 galaxy phone. And believe that updates are part of service delivery, I asked Mtn about it, they don't know much. I know updates take a while (we got Jelly Bean a few weeks later than Europe) but I believe someone somewhere is delaying the Android 4.1.2 update, 4.2 is also out there. Can you please inform me what the system is with these updates? Where does it come from and where is the delay?

I really need answers because our mobile networks don't seem to know.

Thank you!