Can a collective agreement allow an employer to impose daily changes to normal schedules hours of work by the employer with 12–days notice?

Even if article 18 of the collective agreement could be read to allow the imposition of daily changes to normal schedules hours of work by the employer with 12–days notice, the fact remains that the employer representative clearly lead the bargaining agent to believe that the employer would not proceed in that fashion. The bargaining agent relied on that promise when they agreed to the changes to article 18. These facts and the fact that the employer did not pursue a policy implementing that interpretation leads me to conclude that we are faced with a term and condition in force that at minimum could be included in a collective agreement. This situation is different then the one found in UCCO-SACC-CSN v. Treasury Board where the estoppel argument was based on a past practice and the adjudicator found that no detrimental reliance occurred. In the current a promise was made and relied upon.