When a credit/debit card deposit is declined, the funds will be temporarily reserved by your card issuer and, therefore, not available to use. In most cases, the money will be released back into your account very shortly after. However, sometimes the funds can be held longer and the amount of time it takes differs between card issuers.
In the first instance, you should contact your bank and ask for the funds to be released back into your account. If, after 10 banking days you have been in touch with your bank and the funds haven't been released, then please contact our Customer Support team.