Getting **********

Signed up for a R199 20GB+20GB contract in July 2019, but I'm getting billed R300 I have been trying to get this solved since August but nothing is done, all they do is log tickets and send messages to say it's been resolved and still continue over charging me. I have sent my contract, emailed, contacted the Customer service but to this day I'm still getting over charged all I want is to be refunded and charged the correct R199 I signed up for.