Videotron changing contract prices, claiming it was an error

A warning to other customers, Videotron is playing games on agreed prices in contracts.

I received a letter stating that the DUO offer discount of $20 on my internet package is apparantly an error, yet when I signed up for mobile service back in 2014 it was part of the deal. I qualified and could keep the DUO offer if I have a mobile service along with another Videotron service with a minimum of $60 (which I do). 

After years of having this offer and after many changes to my account (being reassured I still qualified for this offer as long as I met the terms outlined in the contract) they've decided to claim it as an "error", how convenient. After speaking with one satisfaction he agreed it was shady and that I was not the only customer affected and calling in, however upon requesting to speak with a supervisor I was hang up on (thanks videotron). 

The second agent seemed to understand right off the bat but offered no advice/no counter satisfaction offer and was not willing to workout something at all. I find it unfortunate that Videotron has finally reached the customer service levels of Bell and Rogers, that is not honouring their own contract and their own terms.