Blocking P2P Services

I am currently in Iraq running a home-type internet service. I am running a 2Mbs down/512kbs up. I am having a large problem in service. I am using a D-Link DI-614+ Router to run a DHCP. I can block unauthorized used by way of MAC filters. However I am having a large problem with P2P services. I instucted the users on my LAN that downloading, online gaming, and webcams are not to be used du to the small upload bandwidth. Is there anything that I can do to make my service run faster by blocking these P2P services? Any help would be greatly appreciated.