Bug on buying unique stash tab

Hi,

I tried to buy the unique collection tab and it displayed an error, so I tried to buy it again. After that, it wrote a message in the game chat that there was some error and wait for purchase completion. It added the tab but after that wrote the message again and added one more tab. I don't need 2 of those tabs, is there a way to refund one of the tabs?

Thank you in advance!