2017 Telkom sim giving us a nightmare

We purchased 2 landline lookalike sim cards with telkom and we wanted to upgrade this to a business suitable package, we were advised to cancel that simcard and we could apply for a new one we did that and but since late 2017 we were billed for this sim to this day and we kept on sending mails which we can provide as proof but alas it never helps, yesterday we received this text..Your account ********** 88 has been suspended due to collection. we have send mails to cancellations dept, agents and we just cant get help if anybody at telkom can read this please may you sort out the issue on our landline the number and tany pther details we are happy to provide the details, the number in question is ********** 014, the number doesnt work so no need to keep it private.