Options are heavily dependent upon your hardware. Some options:-
1) Use whitelist MAC access instead of blacklist. Permit specific known MAC addresses to access Wi-Fi.
2) Hide your SSID though, lots of hardware do not scan for hidden SSID's by default. (If the MAC address is changing which means probably the hardware will also scan for hidden SSID's too.)
3) The best option is:- Use RADIUS and certificates. Very tight access to wi-fi. But it will be difficult to figure out and depends upon your hardware.