Virgin Media Slow Broadband Speed

I have complained to your customer services about 10  times now about slow connection speed .I even used you live help and the chap just cut me off.When i first took out the contract for 1 year for the first 2 weeks i had download speeds of 500kbs the after that the speed has dropped of to what i have now .Today 0.78mb which means about 100kbs as i paid for a 4.4mb line this is hope less .I downloaded a program of the internet to track my internet speed from broadband choices and now have a record of about 200 speed test carried out from about November of last year. After every complaint about the speed for about 5 days the speed would go up to about 3mb and after that back down to less than 1 mb so for the first 2 weeks at 500kbs then the next two weeks at 350kbs and then the normal service less than 1mb for the last 5 months . They told me it was my setup so i bought a new router and then new filters move the main pc to the front room for a month, been told that i have to switch off the router 6 times a day and unplug it so as it reset itself. Unplug all the things plugged into the telephone system and then try it. Every time i complain for about 5 days after the service goes up i even got 1 test that went to "3.9mb.So" surely this proves that my system is ok.