Keef.
That site is not independent so the survey cant be trusted, its paid for by Vispa so its not surprising that they figure high on their own survey.
But Tiscali's position is probably reflective of their competence. It seems that Tiscali have a very poor reputation for service.
Your problems however might not be caused by Tiscali, they might be being caused by BT, it depends who is running the equipment.
If your Red light is flashing that means you are not receiving an ADSL signal, if its connecting but not finding the server then its Tiscalis login service at fault.
I recently talked to a BT engineer and he complained that since the BB supply rules have changed a lot of ISP's are installing their own equipment in BT's exchanges and its causing a lot of problems.
Faults on lines can be caused by all kinds of things, if you want to completly isolate your side then take off the cover of your BT landline box, inside you will find to the bottom left a test socket, plug your modem into that with just a single filter. You will lose all your phone services but do it and test the line speed. If there is a dramatic improvement then the problem is in your house wiring. If there is no improvement then its safe to say either BT or Tiscali is causing you the problem, get an engineer round to sort it out for you, as you've proved its not your wiring you will not get charged for his visit.
Also make sure that you have no high RF noise producing equipment in your house or near your line before calling the engineer, that will kill any signal. The classic proof of this are Christmas tree lights, These produce high RF noise and always kill peoples broadband every year. Complaints soar and when the engineer arrives he turns off the lights and slaps a £100 bill on you for being an idiot. Trust me it happens every year.
Slim slag...thanks for that link, VERY useful.