Home WiFi contract refund

I am very disappointed and angry with the service that I got from MTN, I took a home WiFi contract with MTN on the 31 July 2023 at Carnival Mall. when I got home the WiFi could not connect, I called MTN telling them about the challenge that am facing, they told me there is a problem on their system hence my Wifi is not connecting, I returned the device on the 05/08/2023 to cancel the contract because it was not connecting. They took the device and their sim card back and promised to refund me and till today I haven't got my money back.I went up and down to the shop with my petrol,using my airtime to call them but nothing is forthcoming, the only response I get is that their system is down.I mean what does the system has to do with my refund.The service I received sucks big time.