Contact Tiscali and tell them that you find the quality of their service unsatisfactory, and why, and that you therefore want to terminate the service. If you can, explain your complaints.
Tiscali Customer Services
PO BOX 7206
Milton Keynes
MK14 6XG.
A letter is best but they seem to insist on dealing with people by phone instead. 08707 442 922.
Better still, cancel by phone and back it up with the letter.
If you are a Talk package you will have to contact another provider, e.g. BT and arrange for your voice service to be taken over by them.
If you are not in a 12-monnth contract,tthat is all you need to do.
If you are still in a 12 month contract, they may make you pay for a full 12 months. I am challenging the legality of this in the courts. If I win, there will be a way to get your money back.
Also, If Tiscali do not provide a satisfactory service , they are in breach of contract and you are entitled to cancel without being bound by the 12-month clause. However, it may be a good idea to go through their formal complaints procedure to make sure you are on solid ground and give them a chance to fix things.
If you contact Tiscali, they may tell you that you are caught by the FUP, even if you have recieved no warning emails. Check your Tiscali mailbox. If you are under FUP, ask them when the warning emails were sent and ask for copies.
KEEP COPIES OF ALL EMAILS AND LETTERS. Also make a note of what times of day the service deteriorates.
See http://www.tiscali.co.uk/products/broadband/code-of-practice.html?code=ZZ-NL-11MR