Incompetence from Vodacom Accounts

Shocking incompetence from Vodacom. I received a call in April 2018 asking me to pay a total of R532 (my account was behind in payments) and they would then close my account which i immediately did. Have since received calls from several aggressive staff requesting i pay further outstanding amounts. I explained that my account should have been closed in April after payment received and assumed that it was never cancelled. I requested that telephonic calls were checked to back up my request as these are recorded. I have now been handed over to MBD Inc who i have now called twice (shocking call with staff giggling in the background and call was answered after a delay with a straight "hello") and received different information on both occasions, i have also called Vodacom accounts again! No one seems to be in consensus as to what the next step is and it seems i must pay for Vodacom's staff incompetence in failing to cancel the account. Is this fair? Unfortunately we have two other accounts with vodacom!!!!!!