Just a few thoughts
* Depending on the dollar value of the sale, Canon USA verifies their sales over the phone. They will call and if they do not reach you, they will leave a message for you to call them back. If you don't call back, they will cancel the order.
* The number for Canon USA's verification department is 866-510-1342. It is a very small department (less than 7 people) and they work normal hours, M-F. They are committed to Canon and Canon customers and will do everything they can to make things right. Just be patient and don't take out your frustrations on them. Also, while they can and will assist you, they do not have all the answers about what your bank is doing and why your bank is doing it.
* Know your daily credit limit, especially if you are paying with a debit card. If your order exceeds your limit, it will get cancelled, or your order maybe automatically/algorithmic-ally modified to stay within your daily limit (and if this happens, do not attempt to make another order on the same day without consulting your bank first.).
* Make sure your billing information matches your banking information EXACTLY. If anything - ANYTHING - is off, your order will be cancelled.
* If you receive a fraud detection alert from your bank, it doesn't matter if you approve it, Canon will have already received a rejection from your bank and your order will have been cancelled. You need to contact your bank's fraud prevention department and get a preauthorization for the transaction.
* If your order is cancelled, it will have to be resubmitted. Sometimes it is easier to order over the phone and let someone else do the typing. It is rare with larger, established companies that they have "internet only" pricing.
As for Amazon, be very, very, very careful when spending any amount of money you deem significant:
https://petapixel.com/2017/08/11/fell-victim-1500-used-camera-lens-scam-amazon/I recommend buying gear from brick and mortar companies, keh.com, or individuals I either know or can meet face-to-face.
In the end, you are better off being put off than ripped off...
Of course, though, YMMV ;-)