Battling to get a refund from MTN

On 21/06/23 I mistakenly paid R2790 to MTN on my MTN account. I informed them of this on 26/06/23 and sent all the relevant documentation for a refund as requested by the call center agent while I was on the phone with her. After several calls and being cut off several times on 28/06/23 I was told that they cannot find my email sent on 26/06/23. I eventually spoke to Thato Mamabolo and resent the email that was sent on 26/06/23 to him. He received the email, logged a call and gave me a reference number. This is now 2 weeks since I first reported this and still no refund or any communication from MTN. This money does not belong to MTN - not sure why I am battling to get a refund from them.