The Spain Portal is open for extra 4 days, but the Bull Horns are not dropping from Missions. The Collector is not selling horns, you can't gift horns, and regular Missions are not dropping horns.

STEP 1: Buy for Favor Points.



STEP2: If you get down to zero Horns and click any portal mission, you will get the option to request horns from friends - this option should have been available on the home page...

STEP3: The request button is invisible (see the image)....
...click on it and it brings up the request form!



You can ask for 50 Bull Horns.