I think Teenoni mentioned they are on discord too, so could try requesting an order update/investigation there too.
Also note if the ticket was created on 30/12 they would have been out of the office till 8-12th (maybe even 13-14th), so I could still unfortuntaly see them still processing tickets, as they will still be required to do other things in the day, and i'm pretty sure they do get alot of tickets due to christmas period, postal delays, and just the very slow process of it all from order to dispatch, ect.
Also by the fact you put month first in your date I'm assuming your overseas/international (if i had to guess US), not that that should stop them from replying but there might be a differnt way they process international orders tickets (as in they give UK/local customers a higher pirority)
And it depends what the querey will be, as in whether or not it has even dispatched yet, or whether parcel has or hasn't arrived (say stuck in customs, a random sorting facility), partial cancel of order, refund, damaged item, ect. and whether it is essentailly answered in the FAQ(frequently answered questions) (not that they shouldn't respond but they may lower the priority of messages that are answered in there FAQ)
Again may differ how they do things. I can see them get alot of one liner tickets consisting of wheres my order (when it hasn't dispatched yet cause it has a pre-order or stock wasn't there). They do kinda need a disclaimer saying items may not arrive before christmas or dispatch may take 1-2 weeks for instock items due to distribution center being extremely busy.
There is also there FAQ and that has mention of for cancelling you can email at
shop.uk@alltheanime.com, which if your getting nothing from them you could probably use and just mention everything like order number, problem and probably worth mention the ticket number (if they have ticket number, its a while since ive used there contact form).
I do remember quite a few years back I got slotted into the spam filter, but i think i used either a differnt email or a differnt contact methord and eventually got un-spam filtered.
Also if it has dispatched there is usally a tracking number (in your Account / orders page) that you can find and get updates on that way (not sure how good the tracking is for international though assuming you fall into that catagory), but if its been stuck somewhere for far too long then probably worth mentioning to them to get a faster update.