MTN refund

MTN double debited my account on the 5th of May 2020 due to a technical glitch. Numours Call, emails and Facebook messages later.. I received an email from one of there staff on 17th May that the ticked is closed and that the money should be in my account by now.. Well no payment reflected.. Called customer service again on 18 May. Tells me to wait another 4 days... 14 days of a struggle to get the money owed to me back and I have to wait another 4 days.. 18days wait for money to be paid back that is due to me and was never theirs to take. I'm extremely frustrated.