There is a large COTO Supermarket at the Retiro Train Station adjacent to the Retiro bus terminal.
According to Carrefours store locator map this branch appears to be the nearest store to the Retiro Train Station Dirección: Av. Santa Fe 1954, 1123 CABA
Take the SUBWAY line LINE C (towards Constitución) at the RETIRO station.
Get off at the DIAGONAL NORTE station and combine with SUBWAY LÍNEA D (towards Congreso de Tucumán) at station 9 DE JULIO and get off at CALLAO station.
Walk from CALLAO AV. and CORDOBA AV. until destination.