billing change

A couple months ago I spoke with a team member on the phone because I was upgrading my Modem.

They convinced me to go to the Gig internet and my price would be 90 per month.  This month my bill went up to 110.  I specifically said I was not going to go up if the bill went up after a certain time.

She stated that this was the price moving forward.  Why does it seem that your team members are uninformed or lying to the customers?