Send your coin(s) including the certificate(s) to the bank's headquarters:
Coöperatie Kunst Reserve Bank
1054 JA Amsterdam
BEWARE: State your name and full IBAN-number of the account into which you want to receive the current exchange value of the coin(s).
You can always call +31 (0)6 1226 3331 or send an E-mail: firstname.lastname@example.org