I heard Havdalah but the person saying Havdalah mumbled/skipped a few words should I repeat Havdalah?
Thank you for your question.
When we are being included in someone else’s kiddush or havdala we have to listen to every word that was said. B’dieved though, if the beginning of the bracha and the ending, (Boruch ato Hashem hamavdil bein kodesh l’chol) was heard the person was yotza.
O:CH 271-2, M:B 271-3, Biur Halacha ibid D:H D’ishkash, Biur Halacha 59 D”h v’lo amar, Shar Hatzion 213-20, Shmiras Shabbos K’hilchoso 47-39 ftnt. 180-181, Rav Poalim 2-41.