Item sent back to me

Anyone had this happen to them before?

About a month ago a buyer sent me a offer, which I accepted. They paid and I posted the next day. After 3 days it arrived at the postal shop and they got a message from vinted saying it's there. They were prompted a number of times (as it popped up on mine too saying ready for collection) and they were active everyday so must have known. My messages were also sat on 'read'.

The item sat at the parcel shop for 10 days and on the 11th day said item delivered and I got the money automatically a few days after that, and auto feedback. In all that time they said nothing, but clearly active online.

I thought there may have been an error, since I've collected things before and they've still said they are available for pick up. So just assumed they did actually have it.

It's been a week since I got the funds and super confused I've just had the item delivered back to me at home!

It's all completed on Vinted, saying it's been delivered. So they won't be able to get a refund. So I've got free money and the item?! Weird!!