If a case is settled by agreement and the creditor consents in writing, on such form as the department may prescribe, that the agreement debtor be allowed license and registration, or driving privileges, the same may be allowed by the department, in its discretion, for 6 months from the date of such consent and thereafter until such consent is revoked in writing, notwithstanding default in the payment of such agreement. In the event that the agreement debtor fails to pay any installment as specified, then upon written notice of such default the department shall forthwith suspend the license, registration or driving privileges until such agreement is satisfied as provided in this chapter.