Lag can happen due to a number of reasons, you should always make sure that the problem isn't your tech or provider first. Lag is caused by (simply put) either a lose of data packages somewhere along the way from point A (you) to point X (destination) or transmission of huge datat packs that take a lot of time to respond back while nothing happens (like when you say "hi" on skype and it takes forever till the other person gets it and you get a response).

To find out if you are losing packages along the way you can try to traceroute them. There are tools for it that you can download for free and there are also websites that let you check your connection. The most common problem causing lag is more often than not that your signal transmitting from A to X goes through stations where it loses data. In that case you have to contact your IP to reroute you. Best example for this is if you're being routed through "atlas.cogentco.com" - just google it and you'll see that every gamer of any mmo had trouble with them and lag before.

You really just have to take a look where you're losing data or where the response (ms) takes significantly longer (if you're from europe you should normally don't get over 80ms per destination in the mid tier, US player should probably stay below 20 per station). Based on that info and a google search you can get an idea who is responsible for your lag, more often than not it is not at the game servers end but somewhere along the way (it can still happen, could also be your router though and whatnot).

PS: I didn't read the whole thread just saw people still complaining on the last page so I hope I didn't just repeat what someone else already told you - but without that info there really is nothing the tech team could possibly do for you, there are too many people with different providers and routes and whatnot, just test it yourself, it's easy.