They do have a price reduction policy, since you have 14 days to return it. I'd say that someone was not aware, and that a second call to some other operator or a request to talk with a manager would have done it.
I did call back and I got the same answer from both the sales associate and their manager. Their policy, as described to me, was that I would have to return my lens and repurchase at the lower price. They no longer have that lens is stock, so I would be pretty much out of luck should I send it back and try to repurchase it. I did press the subject with the manager and he was able to hook me up with a UV filter. I accepted it, though I've already got a B+W on it, because he did take the time to work with me on what they could do. I was appreciative of that and I do know that the first level manager's options are sometimes limited. I'll use the filter on my 10-22, or I may just keep it in the bag. Again, I was appreciative that the canon sales team did work with me on this and that they were able to accommodate the price difference in some fashion.