Very disappointed

I would like something to be explained to me. I and my partner open an account on 27/02/2021, we took a bed and an LCD screen. The total of the good was R11 609,97. Than the things came up to R14 594,97 after deposit and trade in. And now the total cost of credit is R26 305,80. The thing which we don't understand why would the interest of two goods be so high. We have have accounts in other furniture shops and we have never had to pay this much. From R11 609,97 to R26 305,80. We understand interest but this is ridiculously high. We are not happy at all. On top of that the bed is starting to cave in and it's not even 5 months using it. And what makes it strange is the fact that due to the nature of our work environment we are hardly at barely at home so it's not used frequently.