Trying to cancel Telkom line

I cancelled our Telkom account on the 22 March 2018 I went into a store and was told to fill in certain forms together with copy of ID and to mail it through . I received a mail saying that my request will be attended to within 21 days . I did pay my account for another 2 months , just to make sure all is correct . It is now Mid August ,I am still receiving invoices , I have called numerous times , resent mails a few times , made complaints . We unplugged the phone , not using it .... nothing has been done to date and am not sure what else I can do . The service we received was from Telkom was to say the least substandard ! Trying to cancel our account has been impossible which I’m sure is due to millions of people cancelling know that you are no longer forced to use this substandard telecommunications company that has ********** South Africans for far to long !