TANs (Transaction Number) can only be used for personal transactions. Your bank will never ask you to enter a TAN for prize draws, security updates or to refund money to your account. Hence, please always use caution if you are asked for your bank details or a TAN when you are not actually making a transaction.
Check the transactions on your account regularly. You can do so both online using our Sparkassen app and by checking your statements. When doing so, carefully check all of your outgoings, as this is the most reliable way to identify unauthorised withdrawals in time. Please contact your Sparkasse immediately if you suspect fraud.