Wireless networks traffic causing slow speeds

Hello, I am using virginmedia superhub which is supposed to give me a max of 30mbps. I use it wireless but am often getting fluctuations in speed - sometimes 500kbps upto 20mbps, nothing consistently close over 20mbps or close to 30mbps. I have bought a powerline kit - "develo olan 200 AV Wireless N" which has improved the speed but I still get fluctuations. Is there anything else that can help me overcome this high traffic? e.g. a wireless repeater/range extender.

Need to call your ISP and find out if its you with the high traffic or them. I only get about 10mbps out of 15mbps from my ISP because they over sold the node and to many people use the internet at the same time. The fine print says "UP TO" there is no garantee that you will have 30Mbps at all times of the day. They only have to provide half of that or 1/4 speed to be in the green. This is U.S. policy i have no idea about other countrys.

Edit: High traffic on the router is diffrent from High traffic on the ISP network. A router shares the speed with whoever else is on the router at the time make sure noone else is useing the router. i.e. unsecured wireless network, family members, guests.

Also you are on wireless any company will blame this for speed issues, hook the PC to the modem and run a speedtest or no company will listen to your complaints.