Pathetic service

In May 2019, I paid my account in full and requested for it to be closed. I then sent the cancellations department an email, containing the proof of payment and received an approval of cancellation email. However, Vodacom now states that I owe them 800 and odd rand for an account which has already been cancelled. Till this date, no-one has gotten back to me with my requests and every time I call, the phone gets dropped when I eventually get through to a consultant. This is now affecting my credit score and shows a bad review on my name. I am honestly unhappy about this as I have all the proof needed. I will now be contacting my lawyer if this matter is not resolved within 48hours.