Write to bethel.
Tell them your father contributes to the running costs, but the elders have stopped him listening in.
Say that you are writing to bethel because the elders are telling you they are following branch directions.
Explain that you have spoken to lots of witnesses at your hall and in your circuit about this and they are all disgusted at the unloving way the elders are abusing their power.
Then tell them that as a consequence your father no longer contributes and can no longer attend.
End by saying that you are only letting them know what's going on, and do not wish to hear back from them.