HIgh ping, not due to DSL line

I guess the title says it all. Since Sunday morning I have an unusually high ping which prevents any form of real-time apps (skype, online gaming, etc).
I contacted my ISP (Vodafone), but they informed me that they found no issues with the DSL line.
I ran all the tests I knew about, and they all confirmed the presence of this problem. Also, pings to 8.8.8.8 have an average travel time of 58 ms.

http://www.pingtest.net/result/83780170.png
http://www.speedtest.net/my-result/2838460918
http://n3.netalyzr.icsi.berkeley.edu...f-49d1-aaa9/rd

One weird thing I noticed while (trying to) play League of Legends, which has a bar measuring ping, is that the detected ping is always stable around 60 ms, even though I'm experiencing heavy lag. Ports used by LoL are:

5000 - 5500 UDP - League of Legends Game Client
8393 - 8400 TCP - Patcher and Maestro
2099 TCP - PVP.Net
5223 TCP - PVP.Net
5222 TCP - PVP.Net
80 TCP - HTTP Connections
443 TCP - HTTPS Connections
8088 TCP - Spectator Mode

I don't think it's a problem related with my PC, but I'll post my system spechs to be sure:

Intel(R) Core(TM) i5 CPU M 480 @ 2.67GHz
8,00 GB RAM
ATI Mobility Radeon HD 6550
Atheros AR9285 802.11b/g/n WiFi Adapter

Thanks in advance!