[Checkpoint]

I did a 1400 euro GPU this way, it went exactly how OP described (3 business days, upper management ecc.) but in the end they refunded me.
the item I sent back was purchased on a completely different friend's account. I also scratched off the barcodes on that item to make it impossible for them to link it to my friend.

It's reassuring to hear someone else has a high value item and succeeded. When the upper management replied to you, did they argue that they had in fact sent the correct item and not what you had sent back? They said in the email that they've discarded the item I sent them, which I find odd.

Would you mind filling me in on a bit more information regarding the conversations you had with them such as the steps you took conversing etc?

I didn't speak with upper management.
The normal rep said "I see that the 3 working days have expired, now I'll ask authorization to upper management and I'll send you an email with the outcome". After 20 minutes they sent me an email with refund confirmation.