I would do some sleuthing to find out why an Italian ATC issue affects VIE-LHR. If BA simply asserts this later, just responsing that it doesn't make sense isn't enough.
By way of example, closing off or reducing airspace over Italy could cause air traffic to be pushed north and thus force reductions in traffic north of the affected airspace because that airspace can't handle the volume. Alternatvely, it is a typo which gains a life of its own.