Nacional usually stocks the Roland brand of mango chutney which is pretty dire. I think Pola sells it too. Bravo might have better choices, and you could also try Supermercado Amigo on Tiradentes, Naco.
These two places are where you are more likely to find a proper brand like Pataks - L'epicier de l'orient, Plaza Paseo de la Churchill on Churchill with Roberto Pastoriza, or Asiatico on Avenida 27 de Febrero with Privada.
https://www.facebook.com/LEpicierDeLOrient
https://www.facebook.com/pages/ASIATICO-東光-環球/116962048347283?id=116962048347283
https://www.facebook.com/supermercadoamigord
Yep, I bought recently in Asiatico, they also have a great mixed pickle as well. Delicious !