Not been to PdC but the chain "Chedraui" I saw in Cancun were large grocery stores akin to small Walmarts. I think you may find them elsewhere.
Yep, Chedraui in PdC:
Tiendas Chedraui, S.A. De C.V.
Centro 45 Av. Sur Esq. C 3 Sur S/N,, Centro, 77710 Playa del Carmen, Quintana Roo, Mexico
+52 984 803 1352
Nice street-view photo of it in Playa del Carmen thanks to google maps, right across the street from McDonalds.