Apparently OnePlus has been hacked and a large number of customer credit-card numbers stolen. http://www.bbc.com/news/technology-42745212

OnePlus has confirmed this on their forums: https://forums.oneplus.net/threads/jan-19-update-an-update-on-credit-card-security.752415/

If you or anyone you know have bought directly off OnePlus; you should consider taking appropriate action. (I’d suggest starting with a careful review of your credit card statements...)