They tacked on ALL the interest from the total when I was late on a payment! After looking it over, I called them up and told them if they want the money for the account, they need to remove all the interest. It was over $2500 more then I financed! Finally after going back and forth, they dropped all the interest and I paid it in full. You have to be careful when dealing with them and others as well. They'll add on as much as they can.You do have to watch the payoff date though, I'm not sure how they do interest. Some will actually tack on the interest from the original amount, from day one, if you don't have it paid off by the end of the promotional period. ouch!