I signed on to Amazon's Mechanical Turk as a worker just to see what it was all about (and to evaluate what the workflows were, so I could recommend it to other

I signed on to Amazon's Mechanical Turk as a worker just to see what it was all about (and to evaluate what the workflows were, so I could recommend it to others). I think I ended up doing a couple bucks worth of work, and applied it to my regular Amazon account. Well, recently I went back on it (after a few years of not using it, although I use my regular Amazon and AWS account all the time). And it said I'm not allowed to take on work, because my payment method has been suspended for a policy violation. Which policy? How do I get it un-suspended? Did someone else compromise it to use it illicitly? Nothing on the page gives me any clue of how/who/what to contact.