Kayak is a ****!

I booked and paid a rental car 5 months in advance, just to arrive in a foreign country on the day of my booking and learn from Europcar that the booking wasn't valid. I had to make a new booking and pay again directly with Europcar so Kayak stole $1000 from me. I've been in contact with them for the past few weeks to get a refund but so far they've just tried to make excuses or shift blame to other parties. These people are ****mers and no one should ever use their service!