Need help!?

I has problem with Internet connection stability:

To describe problem ingame way, the normal ping I used to have 50~60, is now turned into 58~64~72~87~98~108~130... up to 210+. It's almost shows every time different ping, starts from middle 87 pops to low 64, then high 102 and like prox. few times in 1min. sometimes more often it goes up to 180 and more, I've called 5 times to ISP provider, they said from their side such problem shouldn't exist, then I sent my computer to guarantee first time, after that it seemed to work like, but can't be sure since I only checked into server for matter of seconds, now when I wanted to pub it still fuxored. I eventually bought new network card, but even with that I have same shit, it's been in guarantee twice, but this problem seems to be not fixed or their just too noobs to find the problem. Before I reinstalled windows the prox 10-20sec, I was in server, I seemed to have normal ping. But now week later it's fucked again. ET was just example, tried other games aswell, same shit. Connection speed however is not affected from it.

I have scanned my comp over 10 times with 3 different spywares, cleaned temporary files etc, nothing has helped, neither spotted virus.

My connection comes via Modem, modem itself is working fine, tested with laptop.

Does anyone have some idea what could cause such problem? Maybe incorrect Windows reinstall? Something with internet settings? Motherboard? Etc, I really got no fucking clue about this problem