Yes, very similar to you. I made 2 orders for physical gift cards which went through fine. Days/weeks later, I placed 3 orders for e-gift cards over the period of a month, and all were declined. All 5 were using the same method of payment.
After the first e-gift order, I got an email wanting me to provide an alternate email address. This was very unusual/unique, so I called customer service. The guy said "no problem", he would put a note in my account that my email was good and told me the order would go through. But the order didn't go through - soon after, I got a message saying it was declined. I called customer service, told them what the previous person had told me, and since it was clearly their fault, asked if they could make a new order with cards of the same value at the same price. They said they would have to get back to me later, which they did, saying "no", they couldn't.
Weeks later, I thought maybe the previous customer service person fixed the problem but only for new orders, so I tried again. For this second e-gift order, I again received an email wanting me to provide an alternate address. This time, I just followed the email's instructions. However, in about an hour, they declined the order again, for no reason. It was after-hours, so I couldn't call them.
Then I thought, "well, maybe people are sniping them" - buying them too quickly before my method of payment could be charged, since I every time I had placed an order before was during a good sale. So for the 3rd order, I tried to add cards to the cart which were not at the top of the list, then purchase. I also tried using an alternate phone number on the method of payment. However, just like clockwork, I again received an email saying my order had been declined for no reason.
The worst is calling customer service. They are like unintelligent robots. It is an extremely frustrating experience. In fact, they told me the exact same thing they told you, nearly word for word. He told me "it's the system that declines it". I told him I actually ended up buying from one of their competitors (which is the truth). When I asked "so, who's in charge of the system?" (in order to fix it), the guy had no response for me. He seemed to be a very passive individual and/or not truly care about his own company's problems. Actually, every time I call, I oddly seem to get a person with the same personality!
I also pointed out to him that all of my physical gift card orders had gone though, but my e-gift orders had not. He was a little surprised, looked at my account, and said it was true. Thanks, very helpful.
After spending hours of my own time on this problem and shopping for cards I didn't even know I couldn't buy, and the ineptitude of Card Cash's employees not knowing how their own system works (whether they are funneling requests to a 3rd party is beside the point because there is apparently no one who knows how any of it works), I told them I had no choice but to leave a negative review for them. I was frustrated, but I kept my cool. At that point, the phone went silent, and I hung up.