Merchant sold wrong item
 

I tried to purchase a page of Velishoul's Tome from Jade, the jewelcraft vendor in Freeport, for 3 plat, and she instead took 21 platinum and gave me a completely different item. I've noticed similar happening before on other emulated servers, possibly due to multiple people using the same vendor at the same time.

Definitely seen this on Stormhaven.

Yes this has happened to me as well. If I'm going to buy something, and someone else has come up to the vendor, I always close the window and reopen right before the purchase. This is probably not an issue with the 'in stock' items (unlimited quantity).

Seen this happen rarely.

I actually had a similar problem. Sold a few Large Boxes to the vendor, and it treated it as if I had sold Small Boxes instead.

"I'll give you 4 gold, 7 silver per Large Box."

"Okay!"

"You receive 2 gold, 6 silver from Durfy McGurkin for selling the Small Box."

"...HEY!"

On a simialar note, I noticed this morning that I have been getting over charged for stacked item. Bought a stack of Snake scales. Merchant said (and was listed as) 1SP per scale, charged 2GP and some change (silver and copper).