Unlwaful Legal Handover

I have laid a complaint with Cell C in 2013 when I took out a cellphone contract with their one outlets in Brooklyn mall that I have purchased a Sumsung S5 which was said to have Download Booster, simply because the device was not charged I could not verify that indeed the Download Booster is there. I then took the Cellphone back to the store and they wanted to blame Samsung store for their incompetence as they referred me to Samsung to tell them to load Download booster on the device but Samsung informed me that the Feature comes with a device itself. I then went to Cell C to request for the correct item I have requested for and left the phone with them and NOW when I try to do my private credit applications I am told I have a debt of about R10 000,00+ from Cell C. I had requested my bank to cancel the debit until such matter is resolved and now I see Cell C decided to take the law into their own hands and not properly consult me. On occasions in 2014 I had made it clear to their consultants of the situation with this unprofessional conduct from their outlet but it seems like I was not serious. I wrote a mail to store manager in Brooklyn and she is still not acting on the matter