Admission based on academic results

I called the school with enquiry with regards to registration for grade 3 and they advised what documents to as they are currently taking , then i went to the school for registration , at reception they say they don't know if they still have space but i must show them the current school report , only then they will give an answer , gave it to the receptionist and she left to ask the principal and came back saying there is no space. The school is discriminating . That means they take students based on results , so that means my son must not get better education . That is not fair.