Steam Valve Corporation Kept the money in my account Bellevue Washington

I purchase five, $50 each "Fast Cards" for Steampowered.com and opened an account. I read their agreement and didn't like what their requirements were so, I contacted them and cancelled my account the same day I entered my $250.00 cash. Their refund instructions were that I return the cash cards to the retailer but when I approached the retailer, I was informed they do not refund purchases of gift cards.
Steam asked for and I send them copies of the numbers from the cards I purchased for a refund which I never received. It appears they stole my money after they told me I would be refunded the money from my account. I have since sent a letter of complaint to the parent company, Valve Corporation.