Hey @Markuss_17918 thanks for posting here, if you are on a plan that requires a minimum top up of €20 to activate the plan, your plan won't be activated unless you top up by €20 in one transaction.
If you top up by €15 this would be added to your balance however if you don't have a plan your credit may be depleted for out of bundle data which you can check by logging into your My3 account.
If the top up has been applied and used I won't be able to apply a refund however pop through to me here on PM along with your full name, mobile number, address and date of birth and I can check the account for you.
