My family has decided to avoid Amazon as much as possible because they changed their billing system in a manner guaranteed to confuse customers..
First, they do not just ship an order, but ship by some magic optimization algorithms, where they might pick and choose between various of our open orders and ship opportunistically. We do not like that change, but we recognize there is a legit business reason or going that way, so we are okay enough with it..
Second, they do not send you a bill that says "We sent you item A and item B, and we are charging your credit card X and Y". No, they just charge you account. And they send an email "Oh, we just shipped A and C."
So if you are curious about any of the charges to your account, you must manually correlate (1) your credit card bill and its many entries by date, (2) all your original order that have info on item cost, and (3) the various emails about stuff getting shipped to you. If you have many orders, that can be a 4 hour process. If you want to call Amazon and have a question, the friendly person on the other end will be more confused than you, and you get to spend 2-3 hours on the phone, and they still may not have a clue. So you get to have multiple phone calls..
BTW, it is pretty obvious that Amazon must track "We charged X for item A and shipped it date D" for accounting purposes. But they do not want you to know anything about that. You are supposed to obediently pay whatever they feel like charging your account.