I won a contest then I upload all file formats client needed,

after all file uploaded then the client completed the handover process. After 7 days I withdraw the money but designhill declined the payment and they say that : [ EXPLANATION REQUIRED] on warning email sent for Design Submission Policy Violation On Designhill! But to my knowledge, I did not ever Violate the policy on designhill. although it happened without my knowledge & I don't know which policy I violate. Now, What should I do to solved this problem ? Thanks