Well, I take it all back - another incident today that resulted in DD getting so stressed that she ended up with a bad stomach & again the same teacher, which is one of her class teachers. - though DD does say thus teacher is snappy & grisly with all of the class, not just her.
Today's was worse as they were on a school trip, long coach journey & DD really suffers badly with travel sickness & after the letter demand on Friday, I had pre-empted any more problems & wrote a bullet point note explaining what & why I had given DD certain stuff to help minimise the likelihood of her vomiting - it's tried & tested after years of dealing with it & though she will still feel ill, it works to stop her vomiting
Teacher confiscated her iPod, which would have helped a lot by distracting DD, as explained in my letter - she frogmarched DD to the cupboard at the front of the class, whilst shouting at her for not listening to what she had been told, DD had listened - my note asked if she could use the iPod as we find it helps her / so DD was mortified & the teacher refused point blank to listen to DD trying to tell her that it was in my letter.
Followed up getting in the coach & then DD heard her loudly tell the other teacher "oh DD tried to blah that listening to music helps travel sickness, that's a new one"
- no you know it all numpty - it's a well known distraction technique to help stem the anxiety that she will be sick in front of everyone & that will make her feel worse & more likely to be sick
can help her doze off too - we've found it helpful for years, but ironically DDs psychotherapist gave her an NHS sheet this week with it printed on
DD was very upset by this as it was me, not her who had said to take the iPod & my letter explained why & asked if she be allowed to use it - not just for DDs sake, but surely it's better for them if she's not vomiting too 
she felt very upset that she was shown up in the way she was & most if all that she wasn't believed - thankfully as it was an early start, she did manage to doze off anyway, but spent a long time at the venue in the toilet with very bad diarrhoea & felt really awful all day as a direct result of the anxiety she felt over this teachers attitude :( - she looked dreadful when I collected her :(