Did you get names of the Kayak people you spoke with?
If so you could just call them daily so they would move on it. Squeaky wheel style. Go to the refunds dept and not through customer service and find out exactly when you can expect to be reimbursed.
Maybe you can email the President of Kayak or Head of Customer Service
and retell your story and hope they will resolve it.
Post your story on their facebook page. Sometimes that does the trick.
If you come stateside you could file in small claims court.