misleading phone deals

I took a cellphone contract with mtn last year and only now i noticed that i was given a data simcard on top of my contract ,i called mtn and i was told that I have two contracts instead of one and i should call the company that sold me the phone not sure why is they a third party as i had app**** directly on the mtn website the company says my claim is invalid however they are nowhere we spoke about a sim contract at an additional cost ,i have asked to get the recording i am being told that i need to go to a mtn store and it will be at their discretion to give me .please make me understand who exactly do i deal with to get this resolved as now we all playing cat and mouse