several times the transaction has been declined, they are probably have standards to approve it.. I offer you to try another alternative if they are not available , they usually give very minimum support and not very helpful.
My experience with them is strikingly similar.I've had cards declined and after messaging their support, they finally approve it... weird. They're also super weird and inconsistent with ad approvals. I've been pretty dissatisfied with revcontent so far, and they have no support on any forums i can find.