I totally disagree with using Pam, or any other bakers spray on Bannetons. Ew. Maybe that is more foolproof in Fantes' mind, but I think most bakers wouldn't resort to that. Bannetons are expensive, hopefully you haven't sprayed yours with Pam yet.
Use a non-stick type of flour to flour them, rice flour or rye flour is usually what I use depending on the bread. Wheat flour is more sticky due to its wheat gluten, so I recommend avoiding wheat flour on your bannetons.
The imperative part is to form the loaf correctly. You should also have already done your first bulk fermentation in another container, use the Banneton for the final proof.
Richard Bertinet's books have a DVD which shows a decent boule formation technique. You want surface tension on your loaf, it would take too much to describe it in full, but on a floured board, pull the edges inward to the center around the circle, the underside that's touching the floured board becomes the top surface of the loaf, and the surface that's put in contact with the banneton.
It is easy to say flour heavily, if you flour too heavily, you will not get a nicely defined ring pattern. When you turn it out of the banneton you will also get too thick and chunky flour on top of your bread, if you brush that away, say goodbye to those nice rings.
I think where people go wrong and stick to their banneton is using the wrong flour in the banneton, and not using a well formed loaf that is ready for the banneton, the loaf being a little non-stick itself due to being properly formed and having a gentle invisible flouring on its surface, as well as good gluten quality from your technique. Another way to stick to your banneton is to put just beaten dough that's too wet in there. You really want a well formed loaf, with proper gluten worked up, after its bulk fermentation. Then with moderate flouring with a non-stick flour, and no spray, you will have a good result coming out of your banneton.
BTW, what did you get for bannetons from them, did you get some of their Slovakian bannetons - I'm wondering about how the quality compares to the German ones? (I'm assuming when you say bannetons you're talking about the willow type ones, for stripe patterns)
Pam is really the wrong way to go for a banneton IMO.