HELOC product, 20 yrs. 10 years draw, 10 years repayment.

Rate based on Prime.

Repayment period SHOULD have collected 1/120th of original outstanding principal balance monthly, PLUS interest accrued that month on balance.

Repayment mistakenly set up as and collected 1/120th of original principal balance monthly, INCLUDING interest accrued that month.

Now approaching maturity date, and large outstanding principal balance remains.

What would you do to correct?

My thoughts are to calculate the difference between the total interest that should have been paid versus what they actually paid, and then credit principal balance the amount of overpaid interest.

But then we're still left with a sizeable principal balance on the maturity date. Not fair to demand full payment from customer after bank's billing error, I would think.

Any thoughts?

Thanks in advance.

You have a breach of contract. Contact your legal counsel.