Where do I get information on correcting loan payments?

The following auditing services can do a thorough review of residential mortgages for lender calculation errors:
* Mortgage Monitor; 1372 Summer Street, Samford, 06905; (800) AUDIT-USA.
* Loantech, (301) 762-7700.

But keep in mind that these services come with a fee, and your lender should be able to work with you to make your own accurate calculation.