Uncleared account that is settled

My account was handed to them. Received a call stating that I qualify for a discount 02/06/2022. My initial balance 895.66 decrease to 537.40 so i paid 100 into their absa bank to retain the discount and send them proof. End of july they deducted 537.40 instant of 437.40. Now they state that i still owe 258.26, I dont understand where does the balance comes from.