Poor service delivery

I canceled my gym membership in April 2021. In December I realized they were still charging me. Meaning I’ve been paying for the gym that we were not using. R1650 down the drain. I notified them of this Jan 2022. They then said that they would investigate the issue for a refund and call me back. Obviously they never phoned back. So I phoned again May 2022: still under investigation. I was quite cross over the phone and was promised by Me N. Lethuli that she will call me back. She never did. She has also been ignoring countless emails sent by my husband since January 2022. It is now 7 months later, and still nothing. How can a big international company like Virgin have such poor service delivery? If I don’t pay them, I get black listed, but it is ok for them to not refund me back?