Telkom will be held liable for all costs incurred due to incapable staff!!!

My mom was killed in an accident in April so I went to the Telkom branch in the Garden Route Mall when I was out of hospital on 19 June to close her account. PRITTY DOUSE attended to me and after being with her for more than an hour, she assured me that the line was cancelled and that I need not worry any further, explaining the 30 day notice period which I accepted as being normal. I went back to the branch today 16 August to follow up on the status of the line only to discover that, not only was the line STILL ACTIVE, but that for the past month there has been a huge number of calls made on this number (ongoing)! The staff member who assisted me today has assured me that the cancellation has now been done. Now tell me this, WHO is responsible for the rental and usage since the initial cancellation (19 June which means I was responsible up to 19 July ONLY)? I am not going to pay and not a hell will this be set off against the estate! I expect someone to contact me about this personally as there was no "manager" at the branch to handle it today.