Personally, I find it very unsettling when T's change "my time." I have read that structure and consistency are important for clients, and changing is like a slap in the face of consistency.

Also, the other thing that sucks here is that, you really were not given a choice. It was take this time or ?????

I think you need to talk with T about this. Especially your concern that someone else took YOUR spot. I doubt that, but still, your feelings are valid.