Sorry my friend - they have you over a barell - they know this.
Here's cutting to the chase ....
To cancel from a service perspective they need to be in breach for 28 days (you'll find an appointment is normally 3 weeks away unless you jump up and down a bit) - purely coincidence of course.
You can cancel the initial contract within 20 days of "signing up" - my go live date was a day 21
I'm sure that time line is just coincidence (TalkTalk would never set up a business plan that way ... ha ha ha!! - oh yes they would)
My story ends in summation with 6 plus hours on the phone to the total incompetance call centre - 2 open reach visits (each proving the router was the problem in seconds) - being sent FIVE routers that did not work (this is after explaining Einsteins take on insanity !) - many emails from the CEO's office - few online chats - and a visit from a BrightSparks engineer who knew of the router problem as it is really common - two weeks of hell with time taken off work.
The BrightSparks engineer knew exactly what the issue was before knocking the door - it's that common.
Ends with an offer of £10 compensation, that I told them to give to charity as I found it truly insulting.
Oh - about £620 to leave the contract.
The last email from the CEO's office was the funniest of all in that it states that it is "very unusual for this to hapen and take so long to resolve" - I almost neded to change my underwear after reading that - no one can be THAT ignorant - can they?
I remember a lesson once from a great marketeer who taught that you get the true picture of a company on seeing how they handle customers when things go wrong. I believe I now have the measure of TalkTalk.
I found asking for a fault manager moved things 1% faster but faster - and I would call on speakerphone whilst doing something else as it takes so so so long. I would call and ask them what date an engineer is coming.
I wish you well in your quest my friend, but I fear for you
I'll see you in 18 months somewhere else!
My regards