iOS 5 - unable to activate

Hello

Any help here would be very much appreciated. My iPhone 3GS, iOS 4.3.3, iPad baseband 06.15 had been experiencing dramatic battery drain, so after trying everything else I thought the best thing to do would be to restore in iTunes.
By accident I restored to iOS 5.0.1 in iTunes . All was OK until I came to activate my phone. I saw the message "No service" and was unable to activate.

In desperation, I then followed this tutorial:

How to: Fix 5.0 "Searching" or "No Service" 6.15.00 baseband after update! STEP BY STEP
http://www.youtube.com/watch?v=aNK_ZXqF6r0&feature=watch_response

All to no avail. I am unable to activate my phone, it will boot, I then come to the "iPhone" front screen. There I slide to setup, enter my language and country info. I then disable location services, and am able to connect to my wireless network. But then when I reach the "Activating your iPhone" screen, I see the message:

"Your phone could not be activated because the activation server is temporarily unavailable."

It will also state my sim is not valid.

Please help, thank you.

 

Issue fixed. I downgraded to iOS 4.3.3.