I’ve just sold a bed frame on a local selling page. We had to buy a bed frame as a stop gap when the new one we ordered was suddenly out of stock and used it for a few months. The man came to collect it today and took it away to assemble it. I’ve since had a message saying it’s not a king size as I said it was. Our mattress is a king size and we ordered a king size bed. He sent me photos of the bed assembled and it does seem to be a double. I asked my partner and he said ‘well the mattress DID overhang a bit either side’!
I had never even noticed but it looks like the shop sent us the wrong bed months ago and we’ve been using it with the wrong mattress!
I apologised profusely, offered to refund the money etc but he’s getting very aggressive by message, telling me he wants my partner there now to dismantle it at his house. He keeps messaging to ask how long he’ll be, how angry he is that i’ve wasted his time and that I clearly knew it was a double when I sold it to him. He is insisting my partner is there ‘within the next couple of hours’. 
I have been extremely apologetic but i’m a bit shakey now as he knows where we live and I hate confrontation.
AIBU not to send him round?