It's long past time that people stop thinking about class war in terms of wages, benefits and taxes, and start thinking about it in terms of economic and political power. Otherwise you see sh*t like this.

According to the Alberta Labour Relations Board (ALRB), on August 22 an anonymous letter was shared among scaffolders at a Suncor Inc. site in Alberta, Canada, that asked workers to "collectively refuse to work overtime shifts for the purpose of compelling incentives from the Employer, including improvements in compensation or working conditions.” Suncor is one of Canada's largest fossil fuel companies.

According to the board, this resulted in no workers taking on overtime shifts. Ultimately, it decided that the action was illegal under the province's labour laws, which rule out strikes that occur while a collective bargaining agreement is in force and before a vote has been taken.

"The Board finds the Employees' concerted refusal to accept overtime shifts for the purpose of compelling the Employer to agree to terms and conditions of employment, which constitutes a refusal to work, to be an illegal strike," it said in its decision. The board noted that it would file its decision with the Alberta courts, which would make it enforceable as a court order, and violating it would "result in civil or criminal penalties including contempt of court."
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AlumaSafway went on to warn that violation of this order could include consequences such as "discipline or termination of employment" along with a hiring ban "for those who continue to engage in illegal activity." AlumaSafway also threatened legal action "for all damages caused by the illegal strike" which could make workers "personally liable for added production costs, penalties owing to Owner or, even the loss of the contract with our client."

In the worst case, contempt of court proceedings could open up "the possibility of fines and even potentially jail," the company's letter stated.

So blacklisting, fines, and jail time. This looks a lot like labor laws in the U.S. in the 1910's and 1920's.
Now let's fill in some details for everyone.

"It has been 90 [degrees] every day for the past couple of weeks and these guys are out there working hard with everyone else and not getting the same bonus," the user said. "So they started only working the hours required under the contract. 40 hours a week."
The letter—dated August 25—said, "For the last three days scaffolders have refused to work overtime beyond their 10 hour shifts at the Suncor Base Plant site and have refused to accept overtime shifts for the weekend (Fri-Sun on both day and night shifts)."

10-hour shift. 90 degrees heat.