Account suspended

I upgraded my account last week and since then i have not been able to connect to the internet. When I put the sim in a different device i got a message thatmy service had been suspended. WHY? I pay my account every month as a matter of fact I had to replace the sim (PAY FOR) after you did not return my sim after fixing my tablet. The R500 credit on my account i was told i would get after having issues for Months with my tablet-where is that? I paid fot the upgrade and a sim... If my connection is not restored by Thursday you can phone me to arrange a time to pick up the device and CANCEL mycontract. I WILL put a stop payment on your debit order since you are in breach of contract. I want someone to explain to me why my account has been suspended!!!