There are a lot of things that can go wrong at various points in the process of putting the details in the ui and getting a printed card out the other end, and

There are a lot of things that can go wrong at various points in the process of putting the details in the ui and getting a printed card out the other end, and there will always be bad batches. I'm not sure that its a general problem with the paper stock though. Did your client mention the problem to customer service? There's a chance that he/she could get the cards reprinted.