Note that an infringement can be any download (read upload), not just the same file 3 times and it does not have to be the same rights holder in order for an end-user to progress to a 2nd/3rd notice.
122E.
(1) (b) : "the
infringement occurred at least 28 days after the date of a
detection notice issued to the account holder in relation to
the same rights owner, but before that detection notice
expires."