I sort of know how you feel. I have 24/7 access to my team as well, but they switch off and on by weeks. So I would ask at the beginning of the week who had it. Or they did do weeks, till people started taking advantage, so now they trade off days randomly. I've only ever called it twice the whole four years I've been there, but it was just knowing when the people I was close to had it and when they didn't. Now I am terrified to call it in the event of a crisis, because I have no idea who will pick up and whether they are familiar with my case enough to help me.

I'm really sorry you feel abandoned.

Your T is still available to you, just not in the same way as before. I know that it's hard, but change is OKAY. It really is.