Thousands of Medicare part D beneficiaries will soon receive a check in the mail.

The agency said RxAmerica, which is now a unit of CVS, understated the price of medications.

Around 13,000 seniors were overcharged for drugs used to treat epilepsy and symptoms of breast cancer.

The seniors were forced into the so-called "donut hole."

That is a gap in government insurance coverage in which no drug costs are reimbursed.