Ah, similar but different to our system - our kids must do at least 3 but no more than 6 terms of reception (your year zero)... My DD did 2 terms, so was supposed to be a 6 term, so she skipped the remaining year and went into yr1.

If there actually IS a yr2/3 then it's certainly worth talking to them about it and seeing what their reasoning is, why they think this is the better placement and arguing your case if you are not swayed by theirs?