@Manos6, a security deposit through the Airbnb system is just an agreement. It is a "hold" so to speak on that amount, but it is never charged to you. What everyone is trying to tell you is that your host did not receive any money for a security deposit. You did not pay any money for a security deposit. You can look it up in the Help Centre here: https://www.airbnb.com/help/article/140/how-does-airbnb-handle-security-deposits
If you made arrangements outside the Airbnb system, then that is something else, and not something Airbnb can help you with. But if everything was kept on the Airbnb system, you paid nothing for a security deposit, and your host received nothing for it.
You saw that amount on the listing, but you were never charged for it. Another way to check is to look under "Trips" at the itinerary and receipt for that trip. You will see the per-night charges, and the Airbnb service fee, and a cleaning fee if there was one, but no security deposit.
No one is trying to be annoying. Everyone is trying to be helpful.