Direct pronoun has to agree with gender and number of the noun. So, as the noun is: <u><em>cards</em></u> (debit card and credit card), and that is a feminine plural noun in Spanish, then, we have to use a direct pronoun that is both feminine and plural too, and that is in Spanish: <em>las</em>.
Remember that in Spanish mostly the termination <em>-a</em> indicates feminine and the termination <em>-s</em> indicates plural.