INCORRECT CONTRACT LOADED

I pre-ordered a Samsung S22 Ultra in February on the 36 month contract for R699 per month. I kept on asking the person that I spoke to to confirm that the monthly payment is R699 over 36 and he agreed with me numerious times. I surprisingly received the phone on the 2nd of March. However, I found that I am now being billed for the 24 month contract for R1129 per month. I did NOT sign up for this. I have since enquired 3 times (unfortunately only noting reference numbers for 2 enquiries) about getting it corrected and have been told that it will be corrected to R699 per month. I then phone in again on 05/04/2022 and was told that no OTHER PREVIOUS query was longed. Someone needs to get this sorted ASAP otherwise I will take legal action.