Tens of thousands of graduates have been urged to claim money back after it emerged the bungling Student Loans Company (SLC) has taken millions of pounds in overpayments.

A Freedom of Information Act request by consumer lobby group Which? found that at 31 March the SLC had taken £15 million too much from those who had already cleared their debt, up from the £9 million at the same stage in 2009 (see the Student Loans guide).

Over 57,000 borrowers who had paid off their loans were waiting for arefund at the time.

Which? discovered one borrower was owed £3,000 while another was inadvertently making overpayments for 11 months after his loan had been repaid.

How did this happen?

Most ex-students pay money back via their pay packets to HM Revenue and Customs (HMRC) which passes the cash onto the SLC.

Payments continue until the SLC tells HMRC the debt has been paid in full but in many cases the correct messages are not always relayed when balances are cleared.

Which? chief executive Peter Vicary-Smith says: "How is it possible that for at least the second year running the Student Loans Company has overcharged ex-students by millions of pounds?

"We know paying off a debt is a stressful experience, so the last thing people need is to find that they've been paying out more than they need to.

"The SLC must ensure it doesn't keep ex-students in debt for longer than they need to be."

To add insult to injury, graduates can face a long wait after claiming overpayments back. One had to wait over six months for a refund and even then it was two months short.

The SLC has been embroiled in numerous recent controversies, most notably as tens of thousands of students have faced delays of many months before receiving grants and loans to cover tuition and living costs over the past few academic years.

The SLC claims it only receives information about repayments from HMRC once a year because employers make their tax returns annually. It says there is a subsequent lag, creating some overpayments.

What can graduates do?

You can view an estimate of your balance by logging on at Studentloanrepayment.co.uk, but you must be pre-registered (though the site was down at 11am this morning).

However, some MoneySavers have reported the SLC does not always know your balance at the point you ask, due to the lag.

So keep an eye on your most recent statement and what you've recently paid back (from your payslip) to get a better idea of what you owe.

If you're close to paying off your debt you can contact the SLC on 0845 0738 891 to ensure it stops payments.

Graduates with fewer than two years of repayments left can also set up a direct debit. This puts them in control as it is possible to cancel a direct debit when the debt is paid.

If you're owed money, contact the SLC and ask for a refund.

Further reading/Key links

Student loans MoneySaving guide: Student Loans
Student finance guide: Student MoneySaving
Student loans tool: www.studentloanscalculator.co.uk
Student loan help: Should I pay off my student loan?