complainable to MOE.
Yes you should be punished because you cheated. But the degree of
punishment should be within permissible guideline given by
MOE.
But since it is last year... nothing much you can do.
No physical evidence.
School should have a record of you being punished, but those are
"official" records, you maybe beaten 25 times but what is written
down may be less.
Unless 25 is also within allowed limits.
but honestly, your case would be strong if you brought it up there
and then.