Yeah, I'm getting confused, too.
Say I take out a loan for $10,000, which I'm supposed to pay back over 10 years. After 5 years, I have paid back $5000 (plus the interest payments charged to that date). If in the next month I have $5000+change to burn and want to pay off the loan, they are supposed to tell me the payoff amount (which will be $5000 plus the interest on it for that month, say $5050).
Are you saying that what they are doing instead is calculating the interest on $5000 FOR THE REMAINING FIVE YEARS, and using that as the payoff amount? I don't see how that would be legal.