Struggling to get my refund from OVER payment done

So I have been paying a personal loan , until I lost my job, and notified them , and when I started working my account was already handed over to a debt collection which I had to deal with a lady called Riah Nkoana, I did pay my account until I was offered a settlement amount n paid it off.after I paid the account infull I didn't receive a paid up letter, which I continued paying, Riah called me to ask if I received my paif up letter that was sent last month, and I confirmed with her that nothing on my side. She did resend the letter then I confirmed I received it. Now FNB needs to refund me an over payment that was done 25th May 2020, till now am still waiting and emailing Riah everyday n they keep saying Fnb will refund me, what makes me sick when u owe them they will call you everyday for the payment, now they received over payment now its an hustle to pay me back..COLLAB SOUTH AFRICA