I'm looking for some documentation somewhere, or help, on how to integrate a new payment API. I know there are a number already included but I'm using Zombaio and I want to integrate it to handle the upgrades from a free sign up to different levels of an annual membership, and back down to the free level if they don't renew. An email reminder that there subscription is coming to an end would be nice too, but that's another question for later... lol
I've look through the Manual, no help there that I can see. (not even a manual for vB4 yet), searched here and at vbulletin.org to no avail.