Impaq refunded me after I settled the account then said I owe them

I'm so disappointed with impaq, I requested a settlement amount and it was send to me them I payed the R6thousand something that appeared to be the remaining balance, after the money reflected on their account they called me to say they need my account to do a refund and I gave them thinking I must have over payed and they send the money to me but now again I receive a call from my son's school saying they can't generate a report on their side cos they were blocked to access the impaq system, I went through my emails to find an email threatening me of being handed over if I don't make payment, so they are quick to hand people over, same people who are willing to work with them and pay them, impaq says I owe them when I payed and they refunded me, why? I don't inow. why is it an issue if you wanna settle the account they want you to pay monthly