Hey Samuel,
I believe there has been a misunderstanding, the 20-minute minimum refers to the entire experience, including being taken out to sea. The flight time is in fact around 10 minutes on average. All of this depends on weather conditions of course.
Regardless, I'm very sorry that you had a negative experience with us, and if we have miscommunicated anything. Please drop by the next time you're in the area so that we can make it up to you! :)
Best regards.