While visiting Spain/Madrid my partner finally managed to get a pay-as-you mobile that she could charge without requiring a spanish credit card, which never of us have, as we live in the UK.
Anyway, the mobile just cost €20 from Vodafone at El Corte Ingles and the phone can be topped up at ATM’s and shops.. This should hopefully cut down on our roaming charges..
Remember, you need to show a passport or the number will not be registered and you could lose it.