Cancellation of a contract

I've took a contract with telkom and it's a contract of a sim card which they give me 500mb and free minutes to telkom mobile. At this moment I'm unemployed, 31/08/2017 They tried to deduct and didn't get their money. I called and explained that I'm no longer working and would like to pay what i owe and cancel the contract but they told me I cannot cancel the contract unless I provide the letter of service and etc. Which at this moment I won't be able to get it because of my condition. So I paid an amount of R464 and I thought it was for two months and today they deducted R436 and when I called they tell me that the R464 included unpaid fee of R209. I asked again to cancel my contract because I'm no longer working, they told me that to cancel the contract I have to pay an amount of R800 and the remaining months of a contract. To me it doesn't make sense why should I pay for the remaining months because I wasn't even given a phone, it was only a sim card which the can de-activate. This is a day light ******* because I'll still be paying for those months, the difference is I'll be paying them a lump sum without those benefits.