In a manner, I was double-charged on my first purchase in this game for 180 days of daily diamonds. I was having difficulty registering my credit card with Google Play for the purchase, so I switched my phone from WiFi to mobile Internet, successfully registered my card, and the first attempted payment showed "Error" and the second one "Success". I logged in to Dragonsoul right away and received my 180 days. I logged in a few hours later and was met with another VIP promotion congratulations message. Payment history would later show that the "Error" payment was processed after all. For the record, I obviously received a second 180 days of daily diamonds, but I never consented to that purchase.
That same day I submitted a ticket through the game for PerBlue, since it was still their show but not for much longer. I waited a week but got no response. I had much difficulty finding a support email address, but eventually found another ticket system (?) using ZenDesk on PerBlue's own website. Waited another week and got no response. I tried initiating a refund through Google Play, but my claim was automatically rejected almost immediately because I let far too much time lapse. Google Play says they will only process refunds within the first 48 hours of purchase.
My final avenue for recourse saw my credit card credited for the amount of one purchase. I called the customer service number on my credit card and explained my claim to a representative. After I provided enough detail to their probing questions, they must have decided that my case was legitimate. They told me that the transactions wouldn't be cancelled because I did receive what I paid for. That I said I saw a payment error and that I "was a good customer" (for the credit card company, I assume) also factored into the decision.