Union Representation is your Legal Right.

Every employee is free to join a trade union of their choice and to participate in its lawful activities
— Canada Labour Code, Section 8
No person shall seek by intimidation or coercion to compel a person to become or refrain from becoming or to cease to be a member of a trade union.
— Canada Labour Code, Section 96
No employer shall interfere with the formation of a trade union or the representation of employees by a trade union
— Canada Labour Code, Section 94

The right to join a union and to be represented by a union is  protected by the Canada Labour Code. An employer is not permitted to fire employees because they have  chosen to engage in union activity, nor to discriminate against them in any other way because of their  union activity.