Have the same problem i only got my phone three weeks ago though. The thing is i used to be able to check for updates and it would say none available. Within the last two weeks it says check for updates not available.
Check your social applications sync settings. If the "wifi only" box is checked, you won't be able to pull the update. Uncheck the box and restart your phone. You should be able to pull the update. (Can't take credit for this idea -- got it from others when I was having the same problem). Menu, data manager, data delivery, social applications, then uncheck wifi only box.