You are posing a valid and straight forward question ............ Unions depend and must have service fees/ dues paid in order for them to survive in their plush offices and nice salaries, this is all a true statement of fact. While Unions proclaim to save your job and provide representation, the whole story is not always told to the membership that is paying month after month.
The straight cold fact is that your Union will not survive unless they get the funds, however it would be interesting to note whether your MEC or National Officers have acknowledged and confirmed what is in fact happening with your monies. Hold their feet to the fire, demand answers, they are your representation. One thing that you can do and never hardly talked about is to write the Union and request that a portion of your Union fees not be used for PAC purposes, this can and will result in a portion of your Union fees being returned to you, there is a way to dispute this and it is called Germaine and Non-Germaine expenses of PAC fees.