incorrectly billed

in 2014 i took out a contract with telkom with a 5gigs promotional data, January this year ive upgraded that contract via their third-party sell direct, however the person who handled the upgrade didn't removed that promotional data bundles known as ''add-on data bundles'' instead i was charged for it which when i enquired why my bill was too high one of the telkom agent explained that i was incorrectly charged the promotional data and i wasnt supposed to have been billed and immediately asked the agent to log a case to remove the promotional data bill from my normal bill which failed until today now my line has been suspended while the case is still ongoing because i refused to pay for that promotional data leaving me without a phone while the fault has originated from telkom side. i believe this couldve been handled better internally from the day ive logged a case without inconveniencing the customer(me)...