Hi, no success with EE Amber+GDR2 update either. I updated the phone last weekend when I saw on Nokia Care that EE has the Amber update for my black lumia 920. I talked with Nokia Care on twitter and they told me to send my phone to the nearest Nokia Care office. Since I don't have them in my city, I talked on the phone and they didn't take my phone in service without the proof of purchase (that I don't have - the phone it's from UK) - then Nokia Care told me to contact EE to send me the copy of that. I will, but I guess I will have no luck. My phone has warranty by IMEI in my country, but I can't have it without the paperwork.
I got No Service in malls, elevators, closed area and on the road outside the city. With my old HTC Desire Android Gingerbread I have full signal on all the areas with the same SIM card, so it's not the cells or the sim.