Useless MTN

I opened a new contract (hi sense infinity zoom) I received my phone on the 28th of July 2022. I returned my phone to mtn carnival mall on the 29th of July 22, due to the phone being faulty. I received an IRMS number from the consultant, corne nel. I was informed to contact 083135 to cancel the new contract as I couldn't wait for the phone to be repaired. I phoned that number and it directed me to self help with no assistance... I emailed customer care on 3 Aug to inform them with the IRMS number and to cancel the contract (I was still within my 7 days) and 4th Aug they rep**** asking my ID number, which I gave. I never heard anything back. I decided to call head office and they routed me to cancelations department. Where I spoke to a supervisor called Riley Moodley., he informed me, they never received my IRMS number from carnival mall branch and If I cancel I have to pay R7000. The more I explained to him that I was within my 7 days the less he wanted to hear. He then informed me to speak to the carnival mall branch. Of which I still have no joy, I was informed by corne nel at carnival mall branch he will escalate the matter, I had to follow up regularly with no luck. I insisted to speak to the branch manager where the branch of area manager contacted me 2 days later the area manager called me his name is Mark, assured me he will escalate, I phoned them again today 19tje August.... No feedback... I don't have the phone, nor the dim card but yet MTN has the odacity to bill me for a broken phone which I want to cancel and I was within my 7days grace period.... I think MTN is totally useless. Especially the staff of carnival mall. They boast they are such great sales man.... They can't even sort out an issue....