Anyone who has an interest in any money owed can contact your bankruptcy attorney. They can send a letter or show up to your bankruptcy hearing. The court will not make you pay more than you can afford but if they show up to your hearing you will most likely have to pay them back.
Apparently, you have filed for bankruptcy. If you included these creditors as part of the debts you were discharging under the bankruptcy, then your discharge is a permanent order that stops the creditor from collecting. If they are still contacting you, contact a lawyer, FDCPA + violating bankruptcy injunction.
They can contact the bankruptcy attorney if their loans are among those you are seeking to have forgiven as part of the bankruptcy. They can contact the judge if you have incurred new debts with them.