Samsung SGH-X426 / SGH-X427

I have 4 Samsung X427 phones 1 works fine the other three receive the "No response from network" message when trying to access the network. I also can not download ringtones from Cingulars MediaNet. Cingular has swapped out all the phones - problem remains the Cingular techs don't seem to know what to do! And I've found that you can only call Cingular for help when you have an hour or two to kill. Help!! 😡