My other half told me about your post, so I thought I would tell you what happened to me.
I went through the online support pages and got a reply from [email protected].
That was a couple of weeks ago, so I doubt it has changed.
They used to have a good Facebook Messenger reply rate but they seem to have removed that function.
All I can suggest in the meantime is to buy the shipping again and leave a note re the first one on their online support pages.
Keep it simple, they're easily confused, bless them, just tell that you need that order cancelled. If they try and say that it was delivered, then that's another argument.
Can you get screen shots of everything. That will give times and they will know that they couldn't have delivered in that time. (Although you may need to beat them over the head with that bit, lol)
Almost forgot – copy & paste the tracking number, log out, then try to get it to track it. You get different information that way.
Good luck.