You only have two options that i can think off, to install something like Netlimiter on his PC (which you would need to be able to install somehow wihtout him being able to remove it) or to ramp down the Wireless speed on the router which would also have an effect on you if you use Wireless too and are not directly connected.
Qos Cannot be done on that router by the look of it Zingle.
EDIT: assuming its a D-Link AirPlus DI-614+, the manual is
here