Vodacom and my ********** upgrade

My contract with Vodacom came to an end at the end of February 2018, I declined their offer of an upgrade. A ********** upgrade was still done by one of their staff on my account. I reported the matter to Vodacom when a debit order went off my account for this upgrade. After numerous e-mails and investigation by their ***** division, it was confirmed and I was refunded after more than 7 days. On 28 March 2018, the same amount was deducted from my bank account. This is unacceptable and pathetic. I would really like this to end as there could be a repeat performance by Vodacom next month and every other month as well. GIVE MY MONEY BACK IMMEDIATELY!!