Looks like Telitec block p2p
I can't find any terms & conditions on their site but Google shows things like
tellitec internet users feedback : British Expat Discussion Forum
Torrevieja forum and discussion board • View topic - TeliTec ?

You could try changing ports, it might not make any difference but it's worth a try. In LW tools > options > advanced > super really advanced > firewall.
Change LW's listening port to 65000 (or anything in the range of 49152 - 65535) > ok.
Allow this new port number through Windows firewall.

You could also try port forwarding for your router. The instructions are here: Port Forwarding for the Linksys WRT54GL
You'll need to set up a static IP address first: PortForward.com - Free Help Setting up Your Router or Firewall

LW's listening port, port in the 'manual port forward' box & port forwarded within your router setup must all be the same number

Also try connecting at different times of day/night - just in case they're only blocking during peak hours.