so i bought the ipad air with the free t mobile plan. I returned it and got the black air instead. I took out the sim card as thats what the apple employee told me to do. I got home and swapped sims with the one that came with the new one. Now i cant get the network to work. I try loading a page(yahoo) and it sends me to the t mobile login page. i log in and it says my free plan is active. I have tried taking sim out and resetting network without wifi on of course, still nothing. tried calling t mobile and the line is busy? any help is greatly appreciated.