When my Samsung Account expired, my phone has been going weird.

[RGNPAML]

My Samsung account has been expired for a few days now and I don't know why but the day after it expired my phone has been going weird. For example, when something is updating, downloading, an app EVEN IF I'M NOT ON IT, it still does it itself after a short period of time, it goes back to the "Optus Hello ooo screen and the Samsung part after it" but goes back to the lock screen. Not matter, what it just keeps going on
Can someone please help me resolve this issue?!
If you do thank you! Samsung Galaxy S3