"XMR.to allows you to make a Bitcoin payment with the strong privacy provided by Monero. This means that using Monero together with XMR.to, you can pay any Bitcoin address in the world while protecting your privacy."
Send them an e-mail at firstname.lastname@example.org using a burner e-mail, you will likely receive an answer within 48 hours. Make sure to include the following details: most importantly your order's secret key and the address you would like them to send a refund to. Also include your BTC destination address, XMR deposit address and the amount you sent and at what time, if possible.
"Once we get your Monero payment, depending on the amount, we may wait for it to be confirmed (typically just few minutes), and then send your requested amount of bitcoins to the Bitcoin address that you chose."