Support chat exists, you need to jump through hoops and always select "other" and "I have a problem" and stuff like this. I've talked to them multiple times

When I buy products from Amazon, there's some "Get help about this order" button when I see order details. If you pick correct choices you escape the automated chats and they put a human on the chat with you.

You can then explain your issue.

Amazon always fixed my problems, including refunds, replacements. Their chat support is so good I tend to buy with them even when they don't have the best price.

Can you try from Amazon app, there is an option to click to customer service after the click the second button (from the right) on bottom nav bar.

Then you will have many options, scroll down to something else and you will find chat with customer service and then you want to tell the bot straight that you want to be redirected to an agent. From there you can talk to actual human and ask to be redirected or even ask for a call. Though I am not sure if this will be different if you are not prime member. Also there is a way to do that from website but steps would be slightly different.

I had an item vanish in transit to me (in the UK) and support chat (after fighting through some robotic stupidity) very quickly and without fuss gave me a refund on the spot. So humans do still exist and have agency and are reachable in parts of Amazon at least...

I chatted with them recently but it’s like a maze finding how to reach an agent.

It surelly used to exist, I have settled returns, refunds and reacheduling of deliveries through their chat in the past. Last time was 5-6 months ago