TL;DR Amazon charged CC to recover entire promotional discount (including S&S discount) from order that was fully paid by gift card balance and split in 2 by Amazon. Burden of proof on customer for original order total.
I placed an Amazon order the other day, all items had 10% S&S discount, and 5% for total order above $40 (all items were eligible for that). Order fully paid by gift card balance.
A day later, Amazon decides to split shipment into 2. One of the two orders is then <$40, and Amazon charged my card for the total promotional amount from that "separate" order (including both the 10% S&S and 5% that was applied when the original order was placed).
Opened an Amazon chat, and am now being asked to provide proof that checkout amount was less than what is showing in their systems now.
The amazon system was updated after the order was placed, with and increased final amount.
Agent is asking me proof of original checkout amount, as their system is showing only the updated total. I was given a link to provide this proof to support my claim, and I asked why I needed to provide proof at all ..
So it's up to me to proof they have a dodgy practice … (and that the total was less when I went through checkout)?
As it happens I do have a screenshot, but this feels like it should be reported to ACCC?
After a bit of nagging, the agent apologized and promised me $5 promotional credit ..

Your confirmation email after you placed the order would show the total, can you provide them a screenshot of this?