Yes, I have. It was beyond an attitude, it was very aggressive, and I started surreptitiously recording him after he had come around his desk and was standing over me in my wheelchair bellowing at me. I'm quite robust and not easily unnerved, but had good reason to believe he was on the verge of assaulting me. I wanted what he was shouting, and hopefully if he did hit me, the sound of it, caught on tape.
I made the complaint soon after the interview and assumed challenging his behavior would be held against me.
It was investigated including his report, and I wasn't surprised to be told I'd gone from higher needs mobility and care to insufficient points for any award, overnight, despite strong medical evidence and life long disability.
Interestingly is he had unusually IME, stated that nothing unusual had happened and I had left satisfied. He had also made a claim that the medical evidence supplied would have shown would require an actual miracle to have taken place.
TBF once it was realized I had the lot illicitly on tape, and just how bad and extreme his behavior was, and it was provable, I got apologized to, and was encouraged to accept a phone reassessment direct with a case handler. There was an unexpected, but genuine, desire to put things right. Credit where due.
All the other assessors I've had ranged from perfunctory to highly professional.
I was very scared to report him tbh, but I thought about if it affected me that badly, what it might do to someone more fragile, and TBF the case handler agreed.