Charges I don’t know off

I have been paying my subscription every month and mid July 2019 there was invoice for “discount reversals” of more than R200. I never requested any discounts and I don’t know what they are for. I called the call Centre two days ago and spoke to team leader by the name of Evelyn who couldn’t explain to me what the charges are for after the agent couldn’t explain the charges. She promised to call me with feedback and nothing. I am not paying for charges I don’t know. Today I received an sms stating I haven’t paid. I PAID you guys already!!!! The amount reflecting if for discount reversals charges!!! Please sort my account! Do not lock my account also.