We had a bad experience with Ivanhoe Sea Safaris, because the trip did not end as we were otherwise promised. We chosed this company because they promised warranty for whales.
They failed to live up to our expectations as we did not get the money back, but just a new ticket. Therefore, I can not recommend this company when you don't get your money back if you don't see whales. A guarantee in their world means a new ticket and not your money back, as we had expected.