Norman Bisset & Associates (Part of the Nimble Group) Inability to respond and assist to settle account

Norman Bisset & Associates (Part of the Nimble Group) contacted me for a Stuttafords account which i have been handed over to due to non payments after the company closed down. I have been contacted by Yolanda Andisiwe Mthembu (Nimble Group) and Winney Jacobs (Norman Bisset & Associates) to make payment arrangements. I have been given Banking details and have made payment but they are unable to allocate the money???? I need to settle the account and get a Settlement letter but unable to do so since there is absolutely no effective response in getting the matter resolved as it is been a week now.