This is an oft quoted happening in any new system implementation. You have to take the following approach:
a) Is it critical and it depends on your decision - like the date posting (does it matter if Sales if reflected today or tomorrow, if all you are checking is monthly sales), or number of units and price (important and critical unless neglible value).
IN ALL THE ABOVE CASES IT IS BEST TO DO A CREDIT INVOICE, A CREDIT RETURN AND THEN REDO THE PROCESS
a) If it is non-critical, like a dot missing here and there and does not fundamentally affect the accounts, then you can a) mark out the changes in hard copy or b) in all posted items, there is a comment tab and you can fill there (Only if navvision, can mark out somewhere in the main place (like in XL there is a red flag) that a comment is posted it will be used) and probably put what is wrong in the invoice.
IN ORDER TO AVOID SOME OF THE MISTAKES ( I USED “SOME” BECAUSE WE CANNOT AVOID PEOPLE MAKING MISTAKES), STANDARDIZE THE PROCESS AND GIVE A CHECKLIST OF WHAT IS TO BE CHECKED BEFORE POSTING (For eg, Check date is todays, check if shipping date matches with the document, Check if quantity matches with P.O document and so on )
Hope the above is useful.