Billing mess

Dear Vodacom This situation truly blows my mind! All you had to do was credit my account with R500+ for a cancelled contract. But it would seem that you subscribe to the Zuma-method of accounting, because now my bill went from R900+ to R2000+ in one foul swoop. If you need assistance, please let me know, I am an accountant and would gladly explain debits and credits to you, free of charge. Please fix this mess and inform me once you did. This is ridiculous, I have been complaining since 12 June 2018. Regards. Letitia de Kock