I would be telling her "teacher" that you do not want her name shortened and they are to use her proper first name. If you feel you need to explain yourself - tell them she is getting confused with her name. My sister is Elizabeth and always has used her full name, we wouldn't think of shortening it, although other brothers and sisters have shortened versions of their names. My eldest is Robert - and his name only gets shortened when he goes camping with the boys (and that's only been the last twelve months - he's now 16 - gets called Bertie - which coincidentally was my grandfathers name) - my youngest (11) is alexander - and we do shorten that one - he sometimes gets Alex or Zandy or Zander. I have had words with his teacher who referred to him by his surname in my hearing. I was not impressed.

Anyway back to you. I would talk to the teachers and if that doesn't work go to the Centre Director.