The funniest thing about it (in my view) is that BA/Jaguar is just asking for these types of hoaxes by not delivering the miles in the timeframe they promised.

Maybe the next time they do one of these promotions, there will be a meeting at which someone at BA and/or Jaguar will ask:

"OK, so it's agreed that we will wait as long as possible and even a bit past the promised 6-8 weeks. Any downside to this strategy?"

Someone raises hand.

"Yes, I think the downside to delaying everyone's miles past the promised date is that it would lead to a fertile ground for rumours and hoaxes...

"And a fair number of people will believe these rumours and hoaxes, which doesn't do a whole lot for customer goodwill towards either BA or Jaguary... Plus, it will lead to plenty of otherwise unnecessary calls to our customer service reps asking about these rumors and hoaxes that miles will not be forthcoming."