Is this your phone?
I founded the way to unroot my phone.
I plugged my phone into download mode in my pc
i open up kies 3
i click on tools and firmeware update and inisialization
i entered my phone model : SGH-I747M
i entered my phone S/N
And kies automaticly restaure my phone back to its original state (but whit upfate whit 4.3)