Credit Note Issue

I have make the invoice for a sale of room of 1 quanity, let’s say for 100000 now due to some reason customer returns the half money ie 50000 and i have made the credit notw for that invoice now after a month customer want full return and now i have to make remaining 50000 credit now

How will i do that because it is throwing error of Credit Note already made for this invoice as the return will conisdered the item of Sales invoice not amount

Please let me know the solution