I've personally passed through MAD and BCN on Iberia a few dozen times and had my luggage lost twice. Both times there were very strict but manageable steps I was instructed to take with regard to being reimbursed for my expenses and each time I eventually got a check in the mail. I would suggest starting over, call the Iberia desk in the US, ask for the complete instructions and mailing address. After you mail everything in, you can check in about 3 or 4 weeks and they will have a record of receipt of your documents. Keep checking every 2 weeks and eventually they will be able to tell you that a check was mailed on such-and-such date. It does work, they just make it so 99% of the people give up!