Failed promises

I had called in to query why must installment is so high as I only purchase on a 24 month plan and yet my highest balance divided into 24 came nowhere near what I was being asked to pay. I call in and was told I must have purchased for less than R600 because I did not only have a 24 month plan but a revolving plan as well. Now supposedly any purchase under R600 goes into this plan. Now I informed the guy that I never purchase for less than R600, I mean is that even possible at Makro? I told him that I will gladly go through my purchases with him and he needs to tell me where I had purchased for under R600. At this point he asks me to hold so he can speak to a supervisor and after a while he comes back to tell me that my entire balance will simply go over to the 24 month plan. Now I get my latest statement and nothing has changed! What is the point if your contact centre?! I would love someone to contact to tell me how this is going to be resolved.