Here are some links to resources that parents have found helpful.
I don't recommend that you use this letter in its entirety, but you may find some of the ideas it contains helpful in advocating for your child. Tactically, you don't want to be too critical of the school at the outset, but to aim for a partnership where they recognise the special needs of your child and at the very least stop doing things that are actively turning the child off of learning.
A summary of some useful ideas for the ethics and practice of working with gifted children.
The slides from a lecture in Norway about giftedness, the Jante Law and some suggested commitments to gifted education.