upgrade cancellation and refund

Hi

I was called by mobiles plus offered me an upgrade on behalf of MTN and I took the deal . As per the deal I was supposed to receive the handsets in 5 working days from the upgrade date and was further advised that I will only be debited R69 no delivery fees or promo fees .I never received the delivery of the handsets but I was invoiced for R294 which is not even the R69 that we agreed upon , I then followed it up for both the incorrect invoice and the handsets that were not delivered in 2 weeks already .I was sent from pillar to post and I demanded cancellation of the upgrade as the have failed to deliver the handsets and they are billing me incorrectly , been sending mails between MTN channel queries who are responsible for the cancellation and mobile plus who are the once who offered me the upgrade and to date no cancellation has been done nor refund processed , I follow up with both these service providers now and then and I never get someone to take responsibility and do right .

I have been following this up from the 29/11/2017 and today it’s the 16 -01- 2018 and there is no sense of direction , I did consider reversing their debit but I did not want to spoil my credit profile either