Tarnished name

I have a clothing account with Truworths for almost two years now. I have ben consistent with my payments ever since. Then came April month 2022 where I had some financial constraints and paid R1100 instead of R1420. They called me after receiving my payment and explained to them that I will settle it up month end of May. I honoured my arrangement and paid R1820. I was surprised when I checked my credit score with Clear score that it went down, reason being Truworths listed me that I had missed payment. Paying less amount that you are supposed to be paying classified as 'Missed payment'. I am ****ed off with Truworths as they have ruined my credit score. I will be paying off my balance and don't want anything more with them. I will never advised my relatives and friend to open an account with Truworths