Help with eBay dispute please- seller won't post!

[TryingToHelpBut]

I'm not a massive eBay user but I do have an account. DM was buying a gift for my DD so I let her do it on my app using her own card not using my PayPal. This was Sunday night.
Seller messaged me on Monday morning saying 'I can't send until Tuesday, you can cancel if you want' which I thought was a bit odd but I replied saying no worries, I'm not in a big rush for it.
Today they have messages saying 'the posting has gone wrong, you'd better ask eBay for a refund' but won't expand on story. EBay says 'posted awaiting tracking'
What on earth is going on? Is it a scam? I wondered if they sold the item for a better price on another platform and now don't want to sell to me. As far as I can see EBay won't do anything until delivery date has passed but I'm worried now and of course it won't arrive anyway.
Can anyone give me a bit of advice/help. I can't see a way to speak to eBay at all- just a bot that doesn't give me the right options.

I think they don't want to send it. They can cancel it their end can't they?

They have marked it as sent.
You shouldn’t ask to cancel, as you don’t want to cancel. They should have cancelled the sale themselves with something like ‘no longer available’

Take screenshots of the messages and ask them to initiate the refund
If nothing occurs raise it to eBay as not received, there would be a greater delay at least until the ‘dispute’ gets to a person who can read the details or the ‘untracked’ delivery
times out