Incorrectly debited

On the 3rd of December 2018 i called the accounts department to query an incorrect debit order that went off my account and i spoke to a lady by the name of Sally Maenetja. She promised to investigate the debit order and revert back to me on the same day. She indeed investigate the issue and confirmed that i was incorrectly debited and she would then raise a separate invoice so that i can get reimbursed. When i asked when will the difference be paid into my account she advised that she would call me back on Wednesday the 5th of December 2018 to confirm how much they will payback into my account and when they would actually pay that money back. To this day i still have not received any call from her or even received my money back, can you please advise when will this be paid back......