HORRIFIC. I arrived on time and prepared. No line at the counter in Sarasota. I had sporting equipment, and had paid for an upgrade to include two pieces of luggage. The agent, Ozzie, was a bit bumbling, maybe inexperienced. Said my passport was expired (it's a brand new passport that is good until 2035. Couldn't see my upgrade and was insisting I pay $200 for my second bag. I was explaining and showing my receipt. There was no urgency in his process, he called his supervisor twice before he came down. John (the supervisor), arrived and said to me "So you don't want to pay the $200? Well it's too late for us to check you in now".. As he put a separate piece of luggage clearly labeled for my flight on the belt. They wouldn't let me check in, and this made me miss this flight, and my flight to Portugal later that. I ended up having to purchase a whole new round trip flight. Jet Blue takes no responsibility because I booked with Kayak. So I am out $1200 for this trip. Oh and I obviously lost the upgrade I paid for also. Truly a horrible & stressful day. I have booked dozens and dozens of flights with Kayak, and now with so little customer care BECAUSE I had booked with a 3rd party, I will likely only book with the airline in the future. I was in touch with Underpricer who is actually the company that sent flight confirmations, and they "opened a case" and then I never heard back from them except to ask me if I wanted the case left open... but no updates on them working on a refund for me, even though I sent through my upgrade receipt, etc. So it was a 0 stars experience, and I would not recommend to anyone.