APPAULING SERVICE

So what has happened? I have taken out an contract last year May, if not June. This was a sim-only contract for 24 months. So I have received it after a few days and Then I was advised that I should wait for a day for the sim to be activated. But then, it never worked, not even a single day. Called in daily for a follow up, however, I was advised that I should change my setting, of which I did, even got a mifi router but it still did not work. I then went in-store(Golden Acre, CapeTown) and I was advised that they cannot assist me, I would need to call the call center, and I was never assisted. I have asked for the address to return the sim too, however, I have not received the email as promised and then the 10 days call of period was over and I was not able to return it. I have the proof of me calling, the incident numbers and also I have the numbers that I have rang. They have now blacklisted me of which I now cannot take out anything from any service provider or anything. I am very unhappy about this as I have tried my best to get this sorted but there was a lack of service from their side and not mine.