A fido customer service representative lied to me about an offer that sounded too good to be true (30gb/40$), but when I received the confirmation email, it was stated that it's a 50$ plan, which I had never agreed to. Such schemes might help her get extra commission for having upgraded a customers plan, but it only lead to a very unhappy client who's going to change of providers, because doing so is not accetable. Very unprofessional.
Welcome to the community!
I can not comment on what was discussed between you and the agent but from what you mentioned is it possible the plan comes with a $10 discount which would make it $40? The plan change confirmation does not always state the discount but it shows up on your invoice, you can always call customer service and they can look at your account and confirm if it does have a discount that would make the monthly payment $40.
I did explain everything, but they left me with a simple ''sorry'' without giving me a solution to the fault of THEIR agent. This just shows how much they care for their loyal customers (since 2018).