So last week or so, I switched my iPhone 4 to the 2 GB plan from 200 MB. I'm still unclear about the costs for this (e.g., does AT&T add 25$ to the existing 15$ plan, is there a "switching fee", etc.). I switched in the first place because I went on vacation and wanted Wi-Fi on the go with MyWi/TetherMe for iPhone 4. Unfortunately, my usage has slowed considerately in the last few days since I'm back home and with a regular Wi-Fi network. So I want to switch back to 200 MB. I'm wondering about the costs, like I said. Can anyone shed some light on this? Thanks.