School didn't give me all results - lost place at sixth form because of it.

I needed 3 A*/A grades and 4 B grades to get accepted to the sixth form.

I got 1 A*, 1 A and 4 B's and even after speaking to the school, I wasn't accepted as I didn't have the grades.

I realised that one of my results were missing. I contacted my school, they gave me the missing result which was an A*.

I went back to the other school to see if I could enrol to the sixth form despite being a day late, but they now have no places as they gave mine away as I didn't meet the criteria to be accepted.

I'm not exactly looking for advice but it would help, I'm more just wanting to rant.

Edit: I've contacted my school, the grammar school, and the exam board from the missing result. I'm waiting for replies now, but I am considering contacting more people about this huge issue.