My daily routine involves visiting the Trader and buying all gold coin items, because they're cheap and can be used as upgrade materials. Yesterday I was doing it like usual, but halfway into it, the interface suddenly froze for a few seconds as I was tapping. It then refreshed the window and the list of Trader items, which was strange because I don't think it was time for that yet.
The game buffered my taps while I was in mid-purchase as it froze, plus the few taps/swipes I did to try and get the UI to respond. This resulted in me purchasing a purple Healing Stone for 1014 gems. Obviously, I was really upset. Saving up 1000 gems takes weeks and I was intending to use them to get premium hero soulstones, not waste them on overpriced crap that I already have 20 of.
Support refused to undo this because "it would be unfair to other players".
This isn't the first time I accidentally made a wasteful gem purchase in the Trader, but it was the first time it was completely out of my control. I have a suggestion to the devs regarding this. Please organize the Trader into a gold tab and a gems tab and stop mixing the two together. Otherwise I'll just have to stop using it entirely, since it already provides so little value.