Yes, in ks1. I'd raised a few issues about dd with the teacher informally and intended to discuss them with slt as nothing changed.
Then one week another child's dedicated 1:1 was off, and the teacher decided to use the temporary replacement as a general classroom ta. And dd as the 1:1 support for a child with complex needs. Given that when dc was having a bad day it sometimes took 2 experienced adults, it wasn't surprising dd couldn't cope, and after a few days other dc had a bad day.
She did a pretty admirable job, repeatedly telling the teacher dc was getting upset and becoming increasingly violent, but was repeatedly ignored. Eventually she defended herself when dc exploded at her and they ended up fighting.
The teacher reported to me as a minor childish squabble where he hit dd once and she hit back, the numerous bruises she had acquired earlier proved otherwise. Other parent was told her dc had randomly attacked dd, and she'd gone to town on him in defence, with no mention that her dc had only progressed to a violent meltdown because their increasing signs of distress had been ignored. And that the only support was another small child.
My complaint was that the violent situation was one that could easily have been foreseen and prevented. That neither of us parents were given the true story. Socially and educationally other dc needed that 1:1, not a peer doing their work and the possibilty of a reputation for violence. And that neither dc were gaining anything from that method of teaching.
Dd's bruises were pretty conclusive evidence. The work produced by both with dd as 1:1 easily proved they weren't getting the differentiation both needed, along with dd's handwriting on several days of his work. And ta backed up the fact she had done general classroom support, not 1:1.
Don't know about what eventually happened to the teacher, but dd was given differentiated work from a different teacher for the rest of the year, other dc got their 1:1 back. Teacher didn't return the following year. I know other parents had also complained about different issues.
Also complained to slt about a supply teacher in ks2. They were quite insistent dd do something in pe that is physically impossible due to her hypermobility. With the usual ignorant crap that hyper mobility meant she could do it even easier than everyone else. Dd got in trouble for apparently being stubborn and deliberately doing it incorrectly. I put it down to the teachers ignorance on the condition, and tried to politely correct her knowledge, and make her aware that she had basically bollocked dd for having a physical condition that can be disabling in some cases, if just minor for her. I was told the same crap as dd, hyper mobility was apparently a bonus.
We'd also had a problem with same teacher trying to prevent dd leaving for lessons she didn't do with the class, and doing the work set separately for her. The classroom ta had sorted it at the time, but mentioned it to the head for the record when I reported the other problem. Again other parents had complained about other issues. Supply teacher didn't come back but obviously that doesn't prove anything.
Not sure I'd really say I voiced them as complaints, more that I asked slt if I could discuss some concerns.