Ok I have read through this thread and currently I do not even have the option in the menu to change the display name. I have 4 lines on my account and the names need to be changed. Please let me know how this can be achieved ASAP.
I spoke to an agent and we went through all kinds of info and found that my chrome search engine was not showing menu item "change display name" switched to Safari and it worked. Obviously something is wrong with the coding for servers. Chome is a pretty big and widely used Soni would sort this issue out.