MR PRICE SCHEMING EVERYONE

I always thought that Mr price was the best account to have because they give you a credit limit and your monthly installment for example is R115-00 a month which is amazing.. But for years and years I buy on my account pay my account every month but agree to have n Mr price sim card then everything changes then all of the sudden my installments went higher if I buy something on my account.. When I agreed to my Mr price account there was NOTHING said that they will make my installment higher every time I buy something and apparently even if you do not have a Mr price sim card they also make your installment higher.. I was not even informed about that to me they are just TAKING PEOPLES MONEY!!!!! There weren't ever said to me that I have to pay more with my installment no matter how much I bought or how close I was to my credit limit I didn't get asked once to pay more than I normally do I wonder who is doing the people in now....