MTN should have a online cancellation service cause the workers dont do their work

I have 2 contracts with MTN. They first gave me the wrong contract that I could cancel November 2019. When I called to cancel the *** they told me this was incorrect. After a fight and being dissapointed I just left it and told them to cancel the one the that can be cancelled. They cancelled it now I am still being invoiced. I am not going to pay for January invoice E*** on ***.