Kayak is mainly an online search tool. This means that, normally, they display the prices for flights on a number of other flight-booking websites and don't sell the flights themselves. When you've found the flight that you want to buy, you're sent to that flight provider's website to book the flight and Kayak is no longer involved. If you need anything further in relation to your booking, Kayak is not responsible and you'll have to contact the third-party site that you bought the flight from.
At Alternative Airlines, everything is done on our side. We allow you to search for flights and pay with us on our website and we issue the tickets ourselves. This eliminates any distrust that comes from using a third-party website and guarantees that if you have any queries about your booking before or after booking, we'll be able to answer and deal with it directly and efficiently.