Although their online chat assistance was quick, the agent had no idea what "Error ID:500.000888" meant, to which I suggested that although it was probably not her fault she was useless and a waste of time.
So, I called their national hotline. Again, the response was quick, he apologized for the error, said it was a common problem, and suggested I clear my browser cache and restart. Did that with no success. So, according to his recommendation, I will call back this afternoon because they were "having technical issues at the moment".