Bad service, no refund

I was due for an upgrade on my data Sim. A cell c agent called me, I then did an upgrade in December 2020 the upgrade data contact was for R249. January 2021 I got billed R249. Feb, March, April billed R649 which is incorrect and I should be refunded. I've been calling Cell cell customer service since 29 March 2021.Nobody can tell me what when wrong with the billing I call everyday and every time I have to explain myself.. Then they just advise they waiting on a recording.. I'll must wait 24 to 48 hours. I've spoke to 3 managers already at customer service. The whole lot is ***********.