You're not alone!
My daughter was due to switch from TalkTalk to PN Fibre yesterday on my recommendation. Engineer booked between 1300 and 1800 but of course no show. Landline appears to have been switched but no BB since first thing yesterday and no idea of when it will be provided.
She's been given a date of 22 August, no idea why it should be so long when it's their fault.
We tried to do the same - switch from TalkTalk to PN for Fibre. The transfer was agreed on the 18th June - two months ago - and we're still waiting! We've had to put up with very long delays for an engineer, lost orders, lost broadband and cancelled OR appointments.
Our cherished phone number of 15 years got lost in the process. Internet access vanished for 8 days after OR seized the line from TalkTalk without giving proper notice. ("slamming"?) TalkTalk was deservedly miffed as that's apparently not supposed to happen.
That seizing of the line from TalkTalk was about the only thing that's been done swiftly so far!
The transfer to PN has cost us an extra 100 pounds to date, for bills that weren't bargained for. What with double line rentals and double broadband charges payable to both PN and TalkTalk (who should have been given 30 days notice, but weren't). Then there's a 50 quid bill for transferring to PN that was never originally agreed, an unneeded ADSL router from Plusnet, and 3G charges for all the time we were without fixed line internet.
For weeks we've been limping along on Plus Net's paltry ADSL1 service (we did have excellent ADSL2+ with TalkTalk), all the time waiting for another OR appointment to connect the fibre cross ties.
Dealing with the BT Group is as bad as dealing with the state-owned monopoly that it replaced! There's still that same mindset, that same mountain of bureaucracy to fight though, very poor communication, missed appointments, and endless delays.
Ironically, the monopoly that was once infamous for its "excess workforce" outsources much of its engineering work today to gangs of poorly-trained kids who are scarcely breaking even, after they've paid their own diesel bills to visit jobs. The poor sods even have to pay for the wasted fuel when they find that the customer isn't at home!
What a mess!