Then refund me my purchase and wait for another buyer. I bought because I have a need. You can't meet that need, fine. Give me back my money, and all is good. I am not doing you a special favour buying your item and you are not doing me a special favour selling it to me. I have now paid money which will go in your account, not mine.
In any case who on earth has an urgent need for a £2 item? That would be silly, agreed.
I'm talking about I've spent £12+ on your item and I ONLY bought it because I need it fast. You say no. That's your prerogative to run your business (HMRC sees side hustles as taxable now, god help us) that way, but then don't expect me to be happy having handed over my money.
There is also a way of checking specific items on Vinted via Google Lens, so feasibly whilst you're refusing to accommodate my one off request to post quicker, I've discovered Jane6408 has the same item, and is very willing to accommodate my normal request to post a bit faster and will be getting a glowing review from me, plus a follow.
Again a set number of days to send isn't the same as the seller 'can only' deliver near end date.
I understand the Lockers are full thing and there's maybe nothing you can do about that. A seller messaged that her Locker was full. I don't care when that item arrives as long as it turns up, so I messaged 'no problem.' the thing is though you can't tell if the seller is telling the truth or whether it's true. The buyer is at a disadvantage when it comes to posting.