Why is it never their fault?
If the Union was competent, they would have ensured that the running of the ballot was watertight, and so would have ignored any moves by BA. The fact that they are reacting to BA's complaints by rerunning the ballot suggests that BA has a point, which points towards the Union being less than competent.
Oh well, it's their money (actually, of course, the Unite members' money, who should be better served than by this shower)