No. They can't and they won't. Because no cash redemption invloved with IDFC. You can only redeem for vouchers and they also take service charge. Legally, the service you paid for i.e redemption fee here in this case, can't be taken back from you. So they will fall flat in court-of-law.
If you worry that much, reedem all pts, close the account. If they still reach you tell court, an account can be closed when there is no due pending. You can't charge me now. Judge will say, case closed. No more petitions from IDFC will be entertained now.