Pay me back my deposit!

I cancelled my Telkom account in September 2018. I followed all the processes they ask you to follow...got reference numbers for the cancellation... everything...for the next year i was sent invoice after invoice, emails from lawyers asking me to pay 'or else' kind of *******....then i finally get through to a person at Telkom Nonhlanhla Precious Gumede who assures me the line has now been cancelled back dated to Sep 2018...in February 2020....im STILL getting invoices! and i'm told by my ex business partner they are trying to phone me to say they are suing me for unpaid invoices.

Infact if anything they owe me my deposit! How can an organisation be so useless!