Incorrect billing

On 10/2/2015 I contacted Yolande regarding my account. For the past almost 3 years I have been paying more than my monthly installment thus I should have a credit on my account. I took out another contract which we could not activate because apparently I was R 59 in arrears. I requested a meeting with Yolande. She only send me a payment history on 12/2/2015. I again requested a meeting because my calculations differs from vodacom's . I have not heard from Yolande so on 12/3/2015 I again followed up. Still haven't heard a word from Yolande or Vodacom regarding my query.