Double billed and cannot reverse.

I took a 24 month contract of 2 decoders with On Air tv in 2018 up until today they are still debiting and I have been reversing the debits. When I try to call them about it they say they do not have the file for that contract anymore.

So 2020 I was offerred another contract of 1 decoder this time then I took it. So I am paying R179 and another for 10 G data only to find out I took a hotspot thing when at the mall I can down load anything so I cancelled it. So I am left with R179. This month I found they have debited me twice a R179. One went on the 31.05.21 and the other 03.06.21 when I tried to reverse the debit it is not giving me an option to. So I then called the bank they also cannot reverse it. They say it’s a Mandate I agreed with them but I could reverse before this time I cannot. So I have been trying their WhatsApp line and office line. You go through automated they choose billing option then it’s cuts I have tried 10 times I am not getting through these ******.