Useless Telkom

I am so so angry and disappointed in Telkom. I had a data contract of 40gig per month which came to an end in January, I was then called and offered another contract of 80gig at a cheaper price which I accepted and now I regret it! I NEVER HAVE CONNECTION!!! I am being billed for absolutely NOTHING. When I eventually get connection it says my data has run out. A whole 80gig gone when I couldn’t even finish the initial 40gig! How can I cancel this stupid contract?? I am honestly being ********** and funny thing is that I can’t even access the app to see where this data is going or whether I am even getting the data. I want my money back!!!’