I update to iOS 11 and it really messed up my phone. I tried to restore it using iTunes but it didn't help. I got a new phone under warranty and it has iOS 10.3.3. If I use the back up on my iTunes to restore my contacts (cause they are gone) will it upgrade my phone to iOS 11? I want to restore phone from iTunes and put my music and contacts back, but not upgrade to iOS 11. But last back up was when I had iOS 11. Its an iPhone 7 Plus