Coinpayments stole my btc?

So I sent the correct amount and the page indicated PAID. Then I receive an email saying it actually timed out, and that I should claim a refund for the exact amount I just paid... But then it turned out accepting this refund was subject to some hidden fee amounting to around a quarter of the btc I just sent. No one warned me I would be robbed for accepting a refund.

CP support said "It shows that payment was received after the invoice timed out. Sadly, confirmations will depend on the queue in the blockchain and it is out of our control."

I don't understand what just happened. Who is at fault here? Are they blaming the blockchain?