Was affected by this today: was booked BA279 LHR - SJC in F on Sunday 7th January with my colleague, travelling out to San Fran for the JP Morgan Healthcare Conference (massive Pharma / Biotech Shindig so huge demand for flights out there).
No contact from BA, assuming because it was a TA booking - just noticed in my App that the outbound had disappeared! Unable to change myself, but TA got a reroute LHR - LAX (in F) with an economy hop LAX - SFO (rather than SJC) as no Business available.
Not too bad really, as arriving directly into SFO (versus the car from SJC on the original booking) we shouldn't be too badly delayed into the city.
Still annoying, as direct is far preferable, and indeed is what we booked back in May!