Why can you not drive the car? A failing 12V battery will still work for some time.
Also, I am puzzled by your experience. In any case, I just had mine replaced two weeks ago. I received the alert Sunday morning. I opened the app, requested service, confirmed my appointment, and had mobile service replace my battery Monday afternoon. I do not think the whole process could have gone any smoother, especially since support proved fully engaged on Sunday.
[I see your latest response. Have you tried scheduling a replacement at your trip destination? Let mobile service come to you!]