*****ing my money (and credit rating) continuously!

I had a landline/DSL account with Telkom and once my fibre was available in my complex, I cancelled with Telkom, providing my 30 day cancellation, as they request. I sent in my completed form along with my ID on 6 April 2018. I then expected to pay until 6 May 2018, and expected a pro-rata bill for the 6 days in May.

After many emails asking for my acknowledgement of cancellation, social media posts and calls, I kept receiving bills and I kept being billed each month for a service I had cancelled.

Eventually on 3 July 2018, I received an email to acknowledge my cancellation. Great, but they still didn't credit the false invoices I was sent and THEY ARE STILL BILLING ME TO THIS DATE!

I am absolutely furious as I now have a bad credit rating and its just getting worse. I am at my end and don't know what to do to prevent them from A: *****ing my money any further and B: To get them to rectify my credit rating and also credit all the incorrect invoices.

I work so hard to pay my bills and being ****** from in so many ways is just so saddening.

Can anyone help me talk to the right person at Telkom? ANYONE?