Hi Jo,
Requerimiento de pago prestamo must refer to your apartment mortgage. Is it with the CAM? Because if you do not have any mortgage they may have made a mistake.
Just contact them and request an explanation.
In relation with the cards (visa maestro) you will be charged normally once a year, unless they have told you something different. Some banks, if you keep using the card, won't charge you the "fee-cuota" but in a period of crisis now, they will charged as much as they can. It is all depending on the bank and how good you negociate. If you mention to them you will cancel the cards, you might be able to get it for free, not paying an annual fee.
Regards
Maria