Service added to my account against my wishes

The ADSL lines were upgraded in the area. Consultants came by my house and sold me an upgrade, in spite of all my concerns and requesting that the forms only be submitted a month later, so I could first contact my current internet service provider. I contacted the Telkom consultant one hour later and requested that the upgrade not be added to my account. I received confirmation of the service being added a couple of days later. I contacted the consultant again on numerous occasions to remove the service and was assured that his manager would send me an email to confirm that the service was not added. I never received this email in spite of a number of follow up calls to the consultant's cellphone. I cancelled the service at the Telkom shop but received an account today billing me for the service. Trying to phone the call centre number is futile - the phone never gets answered. I believe the consumer protection act allows a client to not be forced into an agreement and a supplier should cancel such contract when instructed by the client. However, in spite of requesting it never get added within an hour, I am still struggling to cancel this!