I was told - and my experience has upheld this - that when online sponsoring does not work the correct response is not to call the 1K line, but to call web support. Web support will put your upgrade request through and it will appear to UA exactly as though you had done it online. If the 1K CSR does it for you, then it will appear unauthorized.

But even with that, I have always told friends that I will only sponsor them for an upgrade if they have the miles to support the upgrade in their own account and are willing to use them.