oh no.....I am so for you, and for your DD. that is awful.
you know my J has to take meds for similar, and all thro reception was on senna and something els (began with M, sorry, can't remember name[blsuh]) and they were great, except for the dinner ladies!
IME you really DO need to spell it out in big letters and words for them to 'get it'.
for instance, the school mine go to have a big 'water as only drink' policy, in keeping with healthy eating. All well and good, but my son, altho is ok drinking water, will not drink enough of it to keep his bowel working so he also have flavoured drinks and fruit juices.............and he needs them at school.
The first week he was full-time, the dinner ladies refused him his drink (he has orange or apple juice for lunch, his water is for break and to sit on his table). He got upset, his tummy aches got worse, and then he also soiled himself which is so upsetting for them regardless of how sympathetic they are cleaning them up.
I kicked off.........and went to the head teacher. I wasn;t rude, but I was angry as I had gone thro everything with the techer and the TA's and the nurse, and yet no-one seemed to think the lunch ladies needed to know, and of course, the lunch ladies take school rules VERY literal, and give no lee-way for those who have extra needs.
They DO understand now!
please go in and 'kick-off'. Not in rude way, but a very concise way and give them complete understanding that if this continues a complaint will go in. Sometimes it is the only way for people to nderstand!
Oh, and IME (over the 10yrs of having children in school), some dinner ladies seem to have gone to the same place that docs receptionists go to train in that special 'god-complex' they seem to excell at....!