contractual dispute with mtn failure to advice client professionally during cellular upgrade

i am currently in a dispute with mtn regarding a migration od penalty fee when i was allowed for early upgrade . the agent never ingormed me that if i upgrade early that is in the 19th month that i would be held liable for eraly penalty. it is almost a month were mtn is giving me the ran arround. simple solution is to draw the recording at retentions with the agent i dealt with, listen to the conversation and make a decision. they want to reverse the issue and that i should have been aware. the agent was suppose to inform me so that i can make an informed decision towards waiting till the time is right to negate the penalty