Here's something I noticed with other China-based sellers, sometimes they receive orders even though the items aren't stock and mark the orders as dispatched before they actually send them to buy themselves time before new stock arrive.
I wished that was the case with my order, but here's what they said:
I just tracked your parcel, it arrived the local post office on 30th,
2015-05-30 16:30:00 LONDON-HEATHROW SHIPMENT IN TRANSIT-DELIVERED BY THE POST OFFICE
Maybe it has a little delay in the post office.
please wait another few days.
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How they managed to track the parcel was beyond me since there's no way to track it using Royal Mail website and they wouldn't give you the tracking URL either. Regardless, they aren't transparent and honest people to deal with!
Well, I just need to find a reliable UK based seller who can provide SKY3DS and R4i Gold 3DS RTS!