Stayforlong Canceled My Booking, Then Kept My $10 Down Payment

I made a one-night reservation at the Hampton by Hilton hotel through the Stayforlong website for June 15, 2016 (as stated). During the reservation, $10 was charged from me as a down payment, and it was stated that the remaining amount would be collected later from the same credit card. When the payment date arrived, I received a message stating that payment couldn't be taken from my card. I then checked my credit card, spoke with my bank, and was told there was no problem with my card or account, and that the issue could be stemming from the website itself.
I sent multiple emails to share the issue I was experiencing with Stayforlong, tried calling by phone, and tried reaching them in different ways, but I couldn't find anyone to respond in any way. As a result, my reservation was canceled unilaterally, and the $10 down payment charged was never refunded — it was essentially seized.
I am requesting both an immediate refund of the $10 I paid, and that the necessary investigations be conducted so that this kind of practice doesn't cause harm to other customers, along with warning potential customers about this.