I remember the exact same frustration. It always feels like your cabinet has been left behind, and there is no-one to ask about an update.
In my case (back at the end of 2010, early 2011), the problem came down to obtaining power from a suitable source - and they left plenty of trails of tarmac in different directions to prove it. Each attempt required a couple of months of planning, waiting for roadworks approval, and getting a team on the job.
In the end, it took 6 months to get sorted (and there are plenty of stories on here of longer), and over that time, the date estimates changed perhaps 10 times, varying from September 2010 to December 2011.
At that time, Openreach only provided loose estimates, each ending at the end of a quarter (end of March, June, September and December). As the end of a quarter got close - to within 5 days or so - they'd run through every outstanding cabinet, and move the date onward by one more quarter. Each quarter would generate howls of frustration on here, but it was all thoroughly predictable.
Contacting ISPs, Ofcom, County BDUK, Openreach or BT's CEO isn't likely to alter the date that things happen; the only result will be to keep you busy & keep you frustrated.
Openreach, for a couple of years, did have a good team responding to emails with details about cabinets - and that dealt with problems like yours. However, as the commercial portion of the rollout has dried up, and county BDUK teams have taken over the public interface, that team has disappeared.
The answer: Don't build your hopes up because of any estimated date that is a quarter-end. Don't let your hopes be dashed when such dates change near the end of a quarter. And stay patient.