Incorrect Billing and Bad Customer Support.

I took out a sim only deal from them, everything was going fine until i get a notice of cancelation from them, anyway i told them go ahead with the cancellation, anyway i owed + R2400 on the account, then last month I received a call from one of their agents informing me that i will be billed R4800, because i did not return their equipment, how do these people do their jobs correctly , when they don't even know what contracts their customers have, just shows the level of people we have working there, On the 12/05/2025, I receive a final demand email, i called in and after i gave all my details the line was cut, while i was holding to be transferred, and not one person called me back, or even bother to respond to my numerous emails, this is embarrassing for a company this size to behave this way.