In appropriate serve by ok furniture

Hi I've taken out a fridge with ok furniture, asking them on the day of application if I can settle after a few months and they said yes, to my surprise the amount that I bought it was for R2600 and after paying for almost 5 months now trying to settle it with the amount of R2600 or less they expected me to pay them R3900 and the cherry on the cake after not doing what they wanted and returned the fridge without any damages they decided to blacklist me and I'm still on judgement because of them. I seriously hope that I can get help with this.