Schools policy on placing according to age- how to get around that?

My daughter was supposed to begin primary school last Wednesday. According to their policy, she would be in grade 4. She started grade 2 in her school in the US this year (which is on level for her age there- the cut off for birthdays is august 31 she was born in december). They want to jump her 2 grades to grade 4 because of their age policy (their age group goes to dec 31). I have called and emailed the principal trying to get her placed in grade 3 and he has not given me an answer. They do not seem to care that she is missing school!
Has anyone successfully dealt with this before? Any way to get an exception to the policy? Who can I go to beyond the Principal?

I believe US schools have a different grade system; the equivalent of US Grade 3 is actually Maltese Grade 4.  so you are looking at a one year jump, not a 2 year jump, so far as I understand.  In my experience, coming from a UK school to the Maltese school here, I went from year x (completed effectively in UK ) to year x+1 in Malta and we could easily have jumped a year and gone to year (x+2) for both my children (both in primary school), due to the difference in what they are teaching.

If it's a Government school, next step is the Ministry of Education or the Minister himself. 
If it's a private or independent school .. nobody I'm afraid.
Classes, as far as I know, are grouped according to Year of Birth not the date and compulsary school age is 5/6, meaning your child is 5 at beginning of scholastic year and will turn 6 by the end of it.