Firstly Tirana1, isn’t BA offering you compensation? Or maybe as this happened 2 days ago it is hard to say so soon. That is your real issue isn’t it, considering the sub couldn’t be avoided.
Secondly, the 767’s don’t operate long haul they operate mid haul.
As for 767 reliability, will admit they are certainly aircraft well beyond their prime, and rather tatty inside, but when it comes to reliability they (speaking globally here not BA specifically) are one of the most reliable aircraft out there, despite the age of many. Also I do check BA source regularly and 767 cancellations don’t standout as being any different from any other aircraft that BA operate. Indeed just now not 1 mention of a 767 going tech in the past 10 days.
PS a friend of a friend of a friend who empties aircraft toilets at LHR told me they were a reliable aircraft so it must be true hey?