You have to keep in mind when you call support, their minimum wage people dont give a S___ about you—and probably dont care about Canon beyond receiving their paycheck. Of course there might be some outliers, but in general if you go in from this POV you'll get better results.
I would have called back mentioning that their must have been a mistake and that you need help. Acting frustrated, making threats, asking for managers, pointing fingers and name dropping how much gear or how long you've been a customer isn't going to get you far. It's just pointless, and they hear it all day. (I assume you must have mentioned all your L glass, like you did in this post) At that point, you've only guaranteed that they will refuse to do anything for you that they dont absolutely have to do. Instead, act concerned about the issue and come at it from the POV that you are relieved to be in contact with the rep and be thankful whenever they do say anything helpful (because everyone likes feel accomplished—especially phone reps, since its a break from the 95% of angry callers). You might even get them offering up solutions you didnt know were possible if you play your cards well enough.
I'm not saying dont be mad—I would be too. But when you show it you get no where (I can speak from experience there lol).