Discount settlement dispute

This serves to confirm my dispute against my discounted offer for settlement agreement with Old Mutual Loans.

I've made the necessary discounted payment in order for the account to have been settled, as per the received sms.

Also numerous communication with their WhatsApp page acknowledging the agreement.

Now I get I have an outstanding arrears amount and it is placing my credit score rating in a bad score.

A window period of 21 days after the payment has been made was supposed to have cleared my name and it's almost 2 months later. With endless arrears messages.

As the required payment was made in order to have my account settled.

Please advise.