Net problems

spixel

Okay heres the jist of it. I live near waterford and have been with 2 providers - digiweb and currently irish broadband ( both 3mb adsl ) . Both have been terrible for gaming with massive ping spikes constantly. When it works fine i get 30-40 ping on uk servers , when its bad ( 90 percent of time ) its 2-300 spiking constantly , doesnt stay at same ping for more than 2 seconds. Any idea what the problem could be , ive rung irishbb up and theyve been completly unhelpful , saying it must be a problem with my computer ive scanned for virus / spyware etc alls fine. They even asked me how much ram i had , when i said 2gig they asked if id thought of upgrading hahaha. Using netgear dm111p modem. What would be the best company to swap to that has stable pings and low contention.