Not sure we have a protocol for such a situation although in general if someone is advertising for themselves, or on behalf of another company, and they are not a vendor, then the posts should be deleted. If the user continues doing so then the user will be deleted.
We put the vendor program in place because vendors like yourself, SPF, Tornado, etc. wanted to be able to have a banner advertisement and be able to advertise on the forum. For vendors that didn't wish to have their own forum, and most don't, we make a special forum where they can advertise their wares, run specials, and I know some vendors routinely and properly take advantage of that.
We also put the Feedback forum in place so that members could provide feedback, both positive and negative, on experience with vendors. That's the place where posts of "I sure love my Borgwald GT, Mr. Borgwald is great" should indexed. However, that doesn't apply to sponsored forums like the RCR and SPF forum where you and Rick decide what sorts of posts you wish to have in your own forum. Rightly so since you pay for them.
But there are always gray areas. Ex: A thread takes off in the All GT40 Forum where someone asks about what GT40 they should buy. The newbie asserts that Tornado doesn't offer disc brakes with their package, and he's looking at a Souther GT because they make their frame from unobtainium. I think that Andy should be able to step in and make a post simply correcting the improper information, and indeed, most times that is what Andy, you, and the others do. As long as the posts in the non-advertising subforums don't get to "advertisey" then it's all good.