No. Nobody can guarantee you a wild animal, and an operator who implies they can is telling you something about themselves rather than about Antarctica.
Wildlife moves with food, ice, weather, breeding success and disease. A good expedition team uses experience, current reports and flexible planning to put you in the right places. They cannot make animals turn up.
Even the common species are reasonably expected rather than certain. And a voyage can lose a planned landing entirely to wind, swell, ice, too many animals on the beach, a protected-area restriction or a biosecurity call.
What you can control is the route, the number of days you spend in the destination, and who is running the expedition. Extra days buy weather windows, alternative sites and another shot at a whale. A route built around the right habitat beats a route that happens to sail in your preferred month.
That last point catches people out. Month sets the broad conditions. Route decides the habitat. A well-designed November itinerary can produce a better wildlife trip than a rushed February one.
If you want a quick test for whether a company is being straight with you, look at the language. Common, reasonably expected, possible, uncommon, rare. Those are honest words. Guaranteed, always, definitely, and you will see are not. Those are the words of somebody selling a picture.