So i have had an iPad 3G for awhile now and have been using the 2gb data plan. I ran out of data day before my auto-renewal date so I decided to buy some more and it took forever so I checked it and I tried it again. Still didn't work after 12 hours. So I decided to cancel my account and I made a new one. It kept giving me errors when trying to create an account but I finally did but no data. So I try and buy some and it keeps saying "AT&T is not able to process your request. We apologize for any inconvenience.
Please try again later. (OEP9999)" after it shows me my bill and I push submit. Please help.

Thanks.

Call AT&T.

I don't know what happened in the first part, but it is possible that they locked your account when an apparently new user tried to activate data on the same device.

Just a guess, but that's all I've got.

Go to settings and reset network settings. That should boot you to the network.

Thank you! I just waited about 12 hours and it worked!