There is a menu Go PTF that will allow you to order directly from your box. It will give you the option you are looking for.
I do have software support.
Simply make a software support call and say you want to order an upgrade. That’s how I’ve always done it.
There is also the Request Order Assistance (RQSORDAST) command. I haven’t used it, but it looks like a reasonable starting point for someone who’s not gone through the process before.