CPT. Santa

I used to play DayZ every day a long time ago, but I quit it for a while & just have came back to it, and when I downloaded it, I realized that it wasn't working, i've been trying to troubleshoot it for days, but no help & I can't seem to stop running into problems trying to download it.. First Commander being gone, now this. Help me please! DayZ begins it's checkmarks & then it suddenly errors.

I'm American, and just recently I bought DayZ SA off steam. I'm having minor troubles with payments though, The first credit card I used unfortunately had an error, so I used another. I have the game and that is not my trouble, my trouble is the fact it says I paid for the game twice, and I've only bought DayZ once. If you could give me a link to the person whom I'd need to call to get this looked over.