Day light ******* *****ing money

I settled my Personal Loan in July, after paying it sent them proof of payment and waited 3 days for the money to reflect on their side. When it reflected they informed me that I have paid more upon confirmation I requested to close account and they refunded the extra amount. Now they say I my payments are overdue. I have proved all detailed date but I say i owe will they are the one who made a mistake. All they do is ***** money from clients