(4)To ensure a prompt and timely handling of complaints, crypto-asset service providers should acknowledge receipt of complaints and inform the complainant as to whether that complaint is admissible without undue delay. Upon acknowledgment of receipt of the complaint, the complainant should also receive the contact details of the person or department to be contacted for any queries related to the complaint, as well as an indicative timeframe within which a decision on the complaint can be expected. Where a complaint has been found to be inadmissible, the crypto-asset service provider should inform the complainant of its decision and provide the complainant with the reasons for the inadmissibility.