The credit card problem does not just happen with RENFE . I´m sure I mentioned this somewhere else , but I tried to book tickets for a big pop concert here in Madrid last year , using a reputable bank/ticket agncy ( ServiCaixa ) . I tried my UK credit card ( refused ) , and my UK debit card ( refused ) .. both of which have very good funds . The operator told me I HAD to use a Spanish bank card .. which is what I eventually did .
Steve