I have also had problems with them. My bank sent full payment on time to Barclays. Barclays sat on the payment and processed it the day after it was due. So I got hit with a late fee and rolling interest charge on my next statement. So I set them up for auto payments 7 days before the due date. They also force you to do paperless statements and make you log in to view your statements. (not sure how many AARP members will do this) But when I looked over this months statement, even though I paid last month off in full a week early, there was an interest charge.
When I called to ask what it was, they explained that if you make a late payment (I didn't, they processed it a few days after my bank sent payment) you get put on basically what is a 3 month probation. They charge you interest for until you have 3 months of on time payment. Even when you pay in full, you still get charged 3 months. Needless to say, I just ordered new cards from Chase and will be cancelling my Barclays account.