Following the well-intended advice on the Wikibook for Assistants in France, I decided to open an account at La Banque Postale. The initial meeting went smoothly enough, bearing in mind I was opening an account as foreigner (non-EU) in a small town that isn't accustomed to dealing with internationals. I wasn't surprised during those following two weeks when I received a phone call every other day at 13h30 telling me "On a besoin une autre formulaire avant 15h00 aujourd'hui" which would have me running around like a madwoman to try and get whatever obscure paper they needed in on very short notice. I figured that this was probably the case for many other assistants so I didn't let it bother me (much). I was thrilled to get a RIB, the requisite document from the bank in time to apply for the October salary advance after some 'minor' problems. I didn't complain all that much when the bank asked me to give the last money I had to support myself as an initial deposit in order to open the account, which would then be held for 'about a week', according to Madame Bank Lady. I figured I could live those 7 days without that money if I was very frugal...
Well, imagine my lack of surprise when I receive another phone call requesting me to come in with another piece of paper, a full three weeks after the initial meeting. I figured we'd sorted everything out but I cycled over as optimistically as I could, paper in bag. I walked in to the bank, preparing to give la Madame said paper when she bluntly told me there has been a problem with my account. I need my Carte de sejour before the head honchos at the bank will even consider opening my account a document which won't arrive until at least the end of December.
So the outfall of her telling me was this: it being October 22nd at the time, my salary had already been released by the Rectorat. Even if I did open another account elsewhere (which I did asap, believe me), I had to wait first for the salary advance to be sent to my inactive account at Banque Postale where it was required to sit for 15 business days before it was returned to the Rectorat who would then direct it to my new, functional account at another bank. A huge problem in its own right, this situation got worse when she told me that they couldn't return the money that they forced me to give them until 3 weeks later... leaving me with no money to live on to this day.
I hope no one ever has to deal with Banque Postale in their lives. It's just not worth it.