I've recently updated my iPhone to 6.1.3 I was 6.0.1 I also had a unlock on my phone that switched me to tmobile so when I updated my service went away any solution on how to down grade back
You should have had a temporary unlock, hence when you upgraded the OS it reversed the unlock status. Just by downgrading your phone will not get unlocked again. You need to unlock it using the permanent unlock service from Mobileunlocksolutions.com and then you need not worry about the upgrading of your iPhone 4S.