Forced debit after settlement of loan facility

Hi This morning i settled my personal loan with Nedbank. A while later they forced a debit on my cheque account for the instalment of the loan i just settled. The funds they took are meant for other urgent obligations. Now i will have to wait for days to get the money back when this problem is not my fault. Nedbank really has a bad retail banking service offering and do not understand their systems to our detriment. They are simply not in touch with the needs of the customer. it is very sad and frankly extremely disappointing.