Management too busy to deactivate and credit account

I upgraded my 12mb wifi line to fiber in February this year. Nepic was supposed to deactivate our wifi line then but instead I am still paying for both services. I have phoned them on Tuesday to ask why we have to pay for a service we no longer use. They said it was a mistake on their side, it was never deactivated. Maria from accounts said she will forward it to management and I have still not received any feedback since. My account needs to be credited for 2 months. I cannot keep phoning every day to hear what's going on. They are wasting my time and money. Extremely disappointed in their service as of late.