Same error with me, sendt a ticket a week ago, this is what i got:

Hail, adventurer!

Thank you for contacting your K2 Payments Team. We have forwarded this request to the appropriate staff for further investigation and resolution. Please make note that it may take some time for this issue to be resolved. We greatly appreciate your patience and your understanding.

Best Regards,

K2 Payments Support

Still waiting h34r: