Multiple Apple Stores

Hi, I'm Argentinian, but now I'm living in Canada.

I have bank accounts and Argentina-related apps on my phone, but also I need Canadian apps.

If I use the Canadian store, the phone only lets me use Canadian payment methods (I cannot use Argentinian ones), and the same if I change to the Argentinian store.

Also, I cannot download or update apps if I'm not in the correct store.

Switching and adding payment methods every time an App is updated is frustrating.

Is there any way that can be resolved? I don't know why I can't use an international card if the card doesn't belong to the country where the store is. And also, having apps from different stores is something I really need, but switching stores makes my every day miserable.

I'm looking forward to a solution to that. Thanks.