Incorrect Billing and Breaching of Agreement

I was contacted "Fodwa" an employee of Sell Direct who initiated a downgrade on behalf of Telkom - my initial intention was to cancel my contract as i urgently need to cut costs. she indicated that the downgrade would cost R269/month which is substantially lower than my R459 i was paying - (downgrade took place on the 20/08/2018. Telkom then charged me R500 odd rand for the pro rata amount and thereafter i was never billed the correct amount as per telephonic discussion. Endless calls to Telkom obviously yielded no results and has gone as far as a agent telling me "we don't see any problems on our side" - yet an sms was sent to me on the 30/10/2018 stating that there is a technical error and they are not able to activate my deal at R269/month but Their team is working on it. Sell direct admits that they do take some blame as they did not check Telkom's promo code used but Telkom needs to rectify this. it has been 4 months now without resolve, feedback or any notification or intent to address this issue. If there is anyone who can possible assist with contact details of organisations where i can legally escalate this issue i would really appreciate it. i have records of all the verbal communications, dates and times for tracing purposes with regards to this issue. its sad to see so many consumers in the same or similar situations and that Telkom simply shrugs off complaints without any concern. Hoping to receive some sort of feedback or direction on the matter. thank you