Bad company that ever existed

I firstly called in as a consultation for an iPhone contract and the lady that signed me up for it told me that I only qualify for an MTN sim card of which I told her that I do not want that and I will then try elsewhere to build up my credit. She then took my details and got me signed up for the sim card without any consent given.

I proceeded to send emails and contact MTN regarding this but they keep telling me that I owe them. How is that even possible because it was opened *****ulently. I will continue to fight this with them honestly.