Well... from my perspective at least... I would say this falls under the category of "let sleeping dogs lie". But that's just me. I don't know if you see a therapist now. What seems to me to be important is where you go from here not why some therapist you saw 5 years ago ignored you & ended up trying to get rid of you. (I know I've seen a few turkeys for brief periods over the years too.)

If you're not seeing a therapist at the present time, & you're interested in seeing one, I would think the thing to do would be to see if you can find one you feel comfortable with. That, it seems to me, is one of the most important elements in therapy. I see you're in the U.K. And from reading various posts, here on PC, I have the impression finding quality mental health treatment can be a challenge. But better to put your time & energy into moving forward, it seems to me, rather than to spend even a small amount of it revisiting something that occurred 5 years ago. At least that's my perspective with regard to your post.