Lost my Web 2 Go service a couple days ago. Kept getting a message saying "you will need a data plan to access t-mobile web". I changed my APN from EPC to internet2 and still got the same message. It wouldn't even allow me to add a new service on t-mobiles website, even if I switched "my phone" to a different phone, the internet plans weren't even listed. When I called up they knew I had an iphone and they stated Web 2 Go is something they are no longer offering. I guess they are forcing any iphone IMEI numbers into their "total data plan". It's now $40/month. Did this happen to anyone else?
Mine has stopped working with the EPC APN last week but I changed it to internet2 and it works fine now. Have you tried reseting your iPhones network settings then trying the internet2 APN?