Telkom *****ing again

<p>Late last year I took a contract ADSL line with telkom ,1st mistake , and after realising i was being overcharged for the data I called another ISP to migrate to their service they then told me to call telkom to cancel their data of which I did even receiving confirmation of the cancellation order via sms.2 months later I am still being billed R350 for uncapped data that i cancelled and now I have to sign a form to cancel it again however when i took up the contract I never signed anything is that even lawful?</p>