Vinted item not sent but shipping time has been extended

[Yorkshireteaalwayswins]

Hi everyone, I appreciate this probably isn't an AIBU but I'm hoping to get advice.
I put on weight over Christmas (like most of us) and the only pair of jeans that fit me wore through at the thighs. I'm hoping to lose weight but needed some jeans for the interim period. Not wanting to spend a lot, I bought some on Vinted. The problem is that the seller hasn't sent them so I caved and bought some new ones.
As the seller didn't send within the allotted time, I thought I would get an automatic refund, as this is what the guidance says, but when I looked this morning, the shipping time has been extended by a week. I googled and it says that I should've been given the option to accept the extension but I wasn't. I no longer need these jeans as I was forced to buy new ones but I have no idea how to stop the sale without getting negative feedback for myself.
Does anyone have any advice/ideas?

You can cancel the sale if it’s not been shipped. Click on the information button(i) in your conversation with the seller and you should be given the option to cancel.

Thanks. Annoyingly i've just had a notification saying it's on its way so I cant now. But its taken 8 days to send and no communication at all so their feedback wont be positive.

I think the issue the seller has had is probably to do with the weather. However, 8 days to ship is a long time and I’d have expected some communication. I’ve successfully rejected a parcel at the door from vinted and it’s just got sent back to the seller and I’ve been issued a refund- worth a try?

I didnt know that was an option but it might be worth a try, thanks!