The obscurity is intentional: The Education Department does not prominently advertise the feedback system because the manual investigations are time-consuming, according to three people familiar with the matter.

That frustrates advocates for borrowers.

“The Department of Education has been running a secretive process that helps only a select number of borrowers get back on track when a student loan company has cheated them out of their rights,” said Mike Pierce, the policy director of the Student Borrower Protection Center, an advocacy group. “Companies need to be held accountable, and the department needs a real solution.”

The Education Department is the largest lender for Americans who borrow for higher education, holding $1.3 trillion in debt owed by more than 35 million people. It relies on a handful of companies hired to service its loans and help borrowers navigate through dozens of repayment options.

But problems are rife, according to government audits and lawsuits against the companies, especially with the Public Service Loan Forgiveness program. The program is intended to draw workers to vital but often low-paying professions with a promise to eliminate their student debt after a decade.

Any mistake along the way can set off a cascade of problems — and so far, nearly all of the 109,000 people who have applied to have their loans forgiven have been rejected, according to the department’s latest data. (As of Sept. 30, only 1,139 had succeeded.)

Most of those who were denied misunderstood or had not yet met the program’s requirements. But sometimes servicers made mistakes, like telling borrowers that they’re on the correct plan when they’re not, or advising them not to consolidate loans that did need to be consolidated to become eligible for forgiveness. For example, anyone who borrowed in 2010 or earlier under the department’s Federal Family Education Loan program must consolidate their loan into a new direct loan.

Such “wrong loan” problems are particularly hard to sort out — unless the borrower finds and follows the complaint option.