But Fosi Audio is not responsible for the logistiscs, customs, taxes etc. as long as they follow the rules and did, what they where supposed to do.
They handed their responsebility over to the logistics company, which ist transporting Your goods, but they are not responsible for the Spanish customs and so on. Thus there exists now a contract between the logistics company and Fosi Audio. They probably have questioned the logistics company about Your goods but I don't know what the logistics company answered, if they did.
Fosi might be reembursed, If the goods are lost, damaged or anything else and they don't reach the address, they have provided on their label, within a given time period, which I don't know.
Usually this "hackling" with Spanish authorities might take several month before anything happens. Even corresponding with Spanish authorities might be a problem and might even "take a long time" due to translation problems on either side. Fosi might have sent their goods to their closest warehouse (Spain) near Portugal to forward it then to Your Portugese address. It's close to impossible for me to know, why their products have been withheld by the Spanish customs authority then. You probably have to wait and try to contact the Fosi service department again and again... It might have to do with unpaid duties or taxes or...
It's your money and you have to spent the time to "fight" for it.... Unfortunately it's (China) a Non-EU country, with another (foreign) language, and it might eventually be hard to get a valid answer from them. Did Fosi Audio contact their Spanish warehouse about it. What did they answer ??? Did You buy it through Kickstarter ? What is Fosi obliged to do as a seller ? How did You pay for it ? PayPal ?