Hi Leone and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, which messages please; incoming from those who called? ...or yours as a greeting?
To save messages from incoming/those who called on a Panasonic KX-TG322NZ, turn on the Answering System by pressing on the ANSWER ON/OFF button of the base unit. If turned on, the ANSWER ON/OFF indicator on the base unit would light up.
And sorry but my participation is strictly limited to technical, repair and/or installation issues.
On the "...credit card has already been debited..." and other billing & payment concerns, please contact Customer Service to have this taken cared of prior to any / all other interactions.