Overpaying compared to what other customers pay - CHECK YOUR ACCOUNT!

I found out today they have been overcharging me. I could 'downgrade' to the same service of 75/75 mpbs for R40 cheaper.

When querying this I got the below response: "promo for new users after you have been using the service. This is how it was. The price you pay its a normal price for the service and months or years after you joined, they made a promo for maybe 3 months I will check for you on the website. So, meaning you were not covered by the promo hence you were not paying the R779"

No sense whatsoever. I downgraded to the same service for R40 cheaper per month. Insane