Some of the worst customer service I've ever spoken to. I bought a couple of Office keys that were already activated. An hour and twenty minutes on webchat to get the support agent to acknowledge that "valid key" does not fix the issue of a valid key that has already been activated.
I used them a lot before this and the keys were always good for games, but now I'm a bit unsure they can be trusted.
Oh also, I forgot to mention. I'd sent a report to paypal, they'd contacted Kinguin and both my orders were marked "refunded." But when I spoke to Kinguin on webchat to check how long it would take, the support agent told me that in this context "refunded" did not mean "refunded." It meant sometime in the next 20 days someone would take a look at my report.