DHCP - block assign IP to specific vendor

Hi all,

I would like to know if there is any change to block auto assign IP for specific MAC address vendor. On my fortigate 100D I have set up DHCP server for guest wifi subnet (Unknown MAC = assign IP) and wifi APs from UNIFI. On the Unifi controller I am able to block, limit speed or block applicaton (facebook etc..) for any connected devices (MAC address). But somebody has WIFI donge/adapter and changing MAC address when the devices is blocked or limmited and he/she is doing very fast. The MAC address starting 02:1a:51:xxxx, 02:12:22.xxxx, 02:94:0f.xxxx, 02:21:10.xxx  etc..... So how can I disable in DHCP MAC address starting 02:xx ? Or can I solved it otherwise (in UNIFI controller) ?

Thank you for any tips or advice.