For banks (or health insurance, EDENOR etc) I suggest to make the acquaintance of someone at the branch when you open the account. Chamuyar them and get their email and whatsapp. If you don't get a gnocci, absolutely everything can be solved almost instantly by a simple email or whatsapp and if necessary, incessant chats of "hola guapo/a, como estas?????". That is how I got my Santander spending limit increased amongst other things and also how I solved an issue with my Edenor factura and made a change to my OSDE plan. Generally I find many people willing to be extra helpful to foreigners here.
Just like ML the key to getting something done is finding a person with whom their is hope and latching on to them for dear life.
Regarding banking and debit cards for online purchases, a good option is Itaú. You can open it online with a DNI and get your debit card pretty quickly with a $30-$40k limit. Each month you get cash back depending on how much you spend and your balance is adjusted each month to keep up with inflation. Their online banking was a bit traumatic to start with, as was their phone help, but in the end the problem just sorted itself out without any explanation.
Brubank as lost refers to also issues credit cards to foreigners but with really low limits - which is good for those times you want to do an online transaction and they do not accept debito.