Bought duplicate item in microtransaction store

I've accidentally purchased two (2) Currency Stash Tabs from the microtransaction store. Would it be possible to refund one of these?

I tried to send an email twice to the support alias but the mail failed to deliver:
"
Delivery has failed to these recipients or groups:

support@grindinggear.com (support@grindinggear.com)
Your message wasn't delivered because the recipient's email provider rejected it.
"