12. The Office may amend or cancel any certificate if, before all the parties have signed the deed of loan authorized by the certificate or, as the case may be, the deed of sale, one of the conditions of eligibility is not fulfilled or an important change occurs in the financial situation of the applicant or in the state of the security offered.
Notwithstanding the foregoing, the amendment or cancellation does not have effect in respect of the lender unless he is notified in writing thereof before the execution of the deed of loan or of the deed of sale.