Incorrect charged for service not provided

On the 28 December 2021 I cancelled my Fibre contract with Vodacom, because they could not deliver the service after 3 months of signing with them. I also requested refund from them because they never provided with the service. They promised to credit my account with the refund. I received an email Account credit was approved but I am still waiting for my funds to reflect on my accounts. When I follow up with the call center, the tell me their are following with the billing team.