Is it allowed to ask my teachers for new predicted grades?

I go the IB and before christmas i asked for my predicted grades hoping they would be high enough to apply during break, and if they were not I planed on asking for new predicted grades if i did well on the mock exams i had before the hollyday. I did this in case my teachers would not be able to correct my mocks in time for the application data, and so i could apply as fast as possible. However, the prdicted grades i was given was not good enough to get into my first choice, far from it, and overall don't reflect how i am doing in my subjects. In two classes my predicted grade is 4, even though i have never resived lower than i five in any of the subjects. And in other subjects the teacher did not have a lot to base my grades of due to corona. I have resived two of my mock exams back allready, and on one of them i resived 7 and on ther other 6, although my predicted grade in those subjects were 4. I asked my ib cordinator if i could resive a new set of predicted grades which would better reflect my preformance in the subjects, but he refused because "To avoid continual giving of predicted grades, we will have to adjust our practice and do like many other schools, give them once only". He never informed us of this rule, and at one point implied that we could at any point could ask for our predicted grades. I understand you can't ask for new predicted grades evry time you do slightly better in your subjects, but i thibk he should have informed us of this rule beforehand. Is this an actuall rule or just common? Is he in the right? I have worked really hard this year and i want my grades to reflect that. Correct me if im wrong, but I've read that it is common that predicted grades are overestimated, but our IB cordinator has addmitted to encuraging our teachers to heavaly underestimate our grades. Predicted gredes are not a common practise in my country, and our IB cordinator (who is british btw) didn't really inform us about them.

Don't worry, In your personal statement write that you are getting 5,6 and 7s in your latest tests. Unis know grades will vary.