Possible, i do that to family members

whenever i start noticing bandwidth going up, kick them out of the network
log into gateway (192.168.1.1 for SLT or 192.168.8.1 for Dialog)
Here's the steps for Dialog HBB (SLT follows same kind of process)
log into 192.168.8.1
Go to Device settings
Identify the device that you want to fuck up
copy the MAC address of that device
Now wifi settings > then MAC filter
select blacklist from the drop down menu
paste the copied MAC address there
it's temporary thing since you can always disable/ re-enable blacklist with a single click