[Paul K]

Doubt if BT would change an install date without notification as all work is managed by a central control and engineers are given set work lists per day. Sounds more like Bulldog failed yet again to sort the proper install date out before imforming the customer.
BT would rarely contact another companies customer to arrange an appointment on their behalf and if the job was in the system for call back it would have been called back as it will go round and round in the callback queue until someone made the call. Jobs don't leave a callback queue untill the call is made and the appoinment etc is booked and the system kicks the job into the queue for the engineer.
Personally I take what Bulldog say with a pinch of salt and having seen the numerous install and billing complaints along with the time taken to get a full and proper resolution from Bulldog, I wouldn't touch them with a very long bargepole.