I had exactly the same issue with my Royal Bank of Scotland account - Gumroad was flagged as fraud (the security people at RBS said they had several complaints

I had exactly the same issue with my Royal Bank of Scotland account - Gumroad was flagged as fraud (the security people at RBS said they had several complaints about Gumroad) and I had to get my account unlocked. People using British accounts - be VERY wary about making payments to Gumroad. I'm waiting till this is available on PayPal or Amazon.