Videotron Cyber Monday Promotion Disaster

I got a promotion on Cyber Monday from Videotron that gets me an iPhone 17 pro + 2 wireless lines + home internet, and the Videotron agent told me that I will get $250 as a cashback credit on the second bill. From 1st December until today 5th March, I have been keeping calling them for various billing issues and incompetent customer service. Today upon checking the voice records of Agent communication with me, they finally admitted that I was supposed to be paid $250; however, they said they cannot honour this because it was wrong information provided by the agent. The company is a disaster, and it has been my headache for the past 4 months. I suggest everyone stay away from this company.