if you are making a complaint or a claim against your bank, do so in writing and present at you bank. Take a copy and ask that to be stamped for your files. The bank of Spain suggests that if you have not received as satisfactory result after one or two months, you can make the complaint via them either in writing or online or at any of their branches. Details on their website. The website is in Spanish with a menu to change to English.
Bank of Spain
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