Telkom billing nightmare

I was on Home DSL Elite which cost about R720 per month. I upgraded to 20Mbs Home uncapped for advertised price of R999 per month which is supposed to include line rental and uncapped internet access on the 7th of April 2018. On the 10th of April 2018 I received a bill for R722 from Telkom for Home DSL Elite subscription for the period of 4 April to 3May 2018. I paid this not knowing when the new Home uncapped billing would kick in. Then on the 9th of May I received a bill for R2773 which included 20Mbs Home uncapped for period 7th April - 3 May 2018 and again for 20Mbs Home uncapped for period 4 May to 3 June 2018 AND my old Home DSL Elite package which is supposed to have been replaced with the 20Mbs Home uncapped upgrade package. I phoned, logged a dispute and also phoned sales as per their instructions and asked for activation of the discount package which is supposed to drop the billing on the Home DSL Elite as it is now covered by the 20Mbs Home uncapped. I was told this would be resolved within 14 working days. I paid in an extra R1400 which I calculated will cover the 2 x R999 for the 20Mbs Home uncapped for the months of April-May and May-June (with some call costs added in). I kept calling for a follow up and kept getting told they will escalate the query. Today I received the latest bill and I now owe R3147 which is the balance of the previous account which was never rectified, plus R1007 for the 20Mbs Home uncapped, AND again R721 for the old Home DSL Elite package which has still not been cancelled. If I pay this, I would have paid Telkom over R5000 for a single Home 20Mbs uncapped over a 2 month period. I again phoned and was told it is still being investigated. At this rate I am cancelling my contract and moving all my business to another service provider.