If your security deposit is managed by SamBoat, a bank pre-authorization is made on the tenant's card before the rental day to ensure the creditworthiness of the cardholder.
If this has failed, you will be notified by email or SMS of this.
From this point on, you have two solutions:
Either you can decide to manage the deposit directly (cheques, cash etc) on the day of the rental
or you can ask the tenant directly from the Samboat mailbox to try again the pre-authorization but this time from another credit card.