Thank you for your response. 

I couldn't give you the bigger picture earlier as there was no space. 

Our bank transactions are automatically downloaded. I then match the payment received to the client and the invoice. There is then always R6.80 overdue on the invoice. We never receive this R6.80 as the bank takes this when debiting the client. 

I need to write off this R6.80 and in the process "close" the invoice as paid completely. 

I currently have about 400 invoices that show partially paid - overdue R6.80

Here is an example