Cancelled my Service but I still Pay ?

I have relocated from Durban to Johannesburg. I called telkom an spoke agent informing that i need to cancell telkom as my service provider. I never used the line or internet for the whole month of January ,however, i was billed for the full amount of R592. Can telkom please give the bill for jan and advise why i am billed for full amount. I am paying for a service that i am not using. Why is this? This is such a ripoff , very disgusted.