Do yourself a favour, go somewhere else. I never even got to be a proper customer. After weeks of messing around, cancelling orders, replacing orders, waiting for engineer visit, non delivery of router and welcome packs, being deliberately lied to on several occasions, they still couldn't sort out the problems. In the end I discovered the issue myself by using details they gave me and setting up an online account. I immediately noticed that the address was completely wrong, in fact it didn't even exist. This is despite my confirming with them on half a dozen occasions that it was in fact correct!
Did they fall over themselves to get it sorted? Not a bit of it. It would take 5-7 working days to change the address that they had screwed up to the correct one and then a further 3 weeks (maybe)for activation. Not going to happen, cancelled everything. I spent around 4 hours on the phone and was passed around to dozens of idiots in foreign call centres who clearly didn't have a clue what they were on about.

Turns out when another ISP checked the line it didn't in fact need an engineer visit at all. It appears they (TT) were checking a non existent line, how does that work?! All in all, it was a complete and utter shambles from start to finish.

Personally I wouldn't touch them again with somebody else's bargepole! Nightmare!

Did I mention that they set up two separate Direct Debits on my account? Despite one of those orders being cancelled (because I found out the first order had not been cancelled as I'd been told) within an hour... Got to get the important bits right, eh? Nice!

As I was setting this up for my daughter I had to give them my address to send the cancellation notice to. Knowing how they screwed up the installation address I spelled it out to her, literally letter for letter. she then proceeded to repeat it back to me wrong, TWICE!

Honestly, you couldn't make it up! Like I all ready said, Nightmare!

Further edit:

After having cancelled the first two Direct Debits, I found later that day that a THIRD Direct Debit had been placed on my account, unbelievable!!!

I have now instructed my bank to block any further attempts from Talktalk to place DDs on my account without my express permission, and trust me, that is never going to happen.

Furthermore, on contacting Talktalk to confirm the cancellation status after receiving the third DD, I learned that they still do not have the correct address for the original installation! And again I find out that they still insist on getting my correspondence address WRONG, AGAIN!

Anyway, it turns out that although I was speaking to "cancellations" they were unable to confirm that the cancellations had actually been done! The best I could get was "They probably have"! So there could be more to come yet.

And I thought people were exaggerating about how terrible TT were!

Be warned, and learn from our mistakes.

EDIT:

This morning my daughter gets a call from an engineer asking "where are you? I can't find your flat" She explained that the order was cancelled. His response was "Talktalk, that's pretty much par for the course then" Shortly after she was called by TT who wouldn't talk to her because she's not the account holder.
I call back and the order has NOT been cancelled and was now being dealt with by their "back room team" I kid you not!

Be warned, and learn from our mistakes.